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In the middle of a torrential rainstorm, Dr. Ross stumbles across a child trapped in a drainage pipe rapidly filling with water. Doug does everything possible to save the boy, Ben Larkin. Harper develops a bond with a young girl with separated parents.

Mark finds himself manning a very crowded ER on his scheduled night off, filling in while Doug is out with whiplash and Susan meets with her lawyer. He tries to juggle hunger pangs, 40+ patients in the waiting room and a never-ending stream of traumas.

Greene prepares to bury his father. Chen worries about Carter's mood swings. After witnessing the interaction between a dying woman and her family, Hathaway realizes she wants her family together and flies to Seattle to join Ross.

Ross and Hathaway's jobs are in jeopardy after their unauthorized treatment of a drug-addicted 7-month-old boy is discovered. Corday loses her sponsorship. Carter suspects Del Amico's boyfriend when drugs are stolen.

Neela and Sam are shocked when they arrive back to the airport with transplant organs only to find that their plane has left them. Dr. Carter gets a surprise visit from an old friend while waiting for his kidney transplant. Dr. Banfield bonds with an abandoned baby boy that is left at the ER.

Benton struggles with the idea of taking a DNA test to determine whether or not Reese is actually his son. As the signs continue to pile up, Kerry and Mark use a fake patient to convince Dr. Lawrence of his Alzheimer's. Carter has trouble persuading a woman from a nursing home fire to sign a DNR for her husband and later is asked to forge charts for a family with no insurance. Carol continues to meddle in Meg's life, having her arrested so that she can be detoxed. Cleo is blamed for an explosion in the suture room but it may actually be Dr. Dave's fault.

Shep and Raul respond to a massive fire without proper equipment, risking their lives to save addicts and their children. Shep will be okay, but Raul has third-degree burns covering his body; it's only a matter of time. The ER is flooded with burn victims. Chloe returns to Chicago. Doug is stood up by his father for a basketball game.

On Thanksgiving Day Carol goes into labor. She's able to get to the ER only thanks to Luka's help. She delivers the first baby in the ER, but the second causes some trouble. Greene leaves Elizabeth to deal with his father and daughter, as he rushes to assist Carol.

As the result of a school shooting, Kovac and Benton care for the gunman and his victims. Abby discovers that Carter has been illegally injecting pain relievers. Greene and Weaver confront Carter about his problem, and Weaver orders him to enter a drug rehabilitation center or leave the hospital permanently.

The ER is flooded with foster care home residents, attacked by a shooter bent on tracking down his son, who , with the help of Dr. Green, was put into the foster care system amid allegations he was being abused by his father.

Chaos reigns in the ER when two prisoners are brought in for treatment, but instead plot a violent escape. Their desperate actions place one doctor in harm's way, and forces one nurse to become a tool in their plan.

The 15th and final season of ER begins with the devastating repercussions of the ambulance explosion. As Morris and Neela do everything they can to save a wounded colleague, Abby treats a young girl injured during the blast.

Carter faces his last day in the hospital with aplomb, harshly grading Benton on an evaluation report. He later rescinds the report after finding out that the surgical sub-I is his. Carol faces wedding day jitters, culminating in Tag's deciding to call off the wedding. Chloe disappears again, abandoning little Susie with Susan. Dr. Swift changes his mind and decides to support Mark. Jake visits Doug.

The hospital suffers through a series of power outages. Carol's decision to send Doug a fax about her pregnancy is thwarted by the power outages. The staff is on alert after a raped and beaten patient is found in a hallway. Romano begs Corday to stay in trauma. Carter and Roxanne break up. Carter and Lucy treat a pheromone saleswoman.

A day's worth of trauma takes its toll on the men and women of the ER. Dr. Greene looks into leaving the ER and joining private practice. Among other events, multiple casualties are brought in when a building collapses. New medical students report for duty, including Dr. Benton's new trainee, the young and inexperienced John Carter.

A severe blizzard leaves the ER utterly devoid of patients, leaving the staff free to goof off. In the middle of their fun, a call comes from dispatch, informing the ER of a 40-car pile-up with dozens of casualties. The ER goes from being deserted to capacity. All surgeons are called in. Bob surprises everyone with a quick and life-saving decision. A new doctor, Angela Hicks, arrives just at the right time. Ross and Linda return from the Caribbean just as Carol makes a surprise announcement.

Kovac and Haleh take care of Hathaway's twins so the new mother can finally get some rest. The job transfer for Carla's husband does not get approved allowing Reese to stay in Chicago. Lucy endeavors to get a heart transplant for a young woman and goes to Romano's house begging him to perform the surgery.

Just when the ER is understaffed and swamped, two children who were brought in turn out to have full blown smallpox. The entire ER must be locked down. The staff needs to improvise while they battle not only the disease but also frayed tempers.

When a torrential rainstorm pounds Chicago, patients deluge the emergency room while Weaver speeds to an accident site. There, she finds a pregnant woman, Vicki lying injured inside a wrecked ambulance while live power lines spark. Fourth-year student Michael Gallant makes a dangerous decision in order to help.

Greene assists paramedics in treating injured children at a school bus accident. En route, Doug and Jeanie survive their own accident. Kerry stops Doug from treating Jeanie...or any other patient. Doug decides to resign and leave Chicago for the Northwest and asks Carol to come with him. She decides against it, but he leaves anyway. Carol steps down from running the clinic so that Anspaugh will keep it open. Jeanie discovers she may have contracted hepatitis. Hospital janitor Mobalage's wife is stabbed.

The ER docs tend to three teenagers who were in an accident on the way to their senior prom. Greene and Carter treat the most severely injured, a boy suffering from third degree burns over 80% of his body. Benton receives the ER trauma fellowship. Carol finally tells Doug about her pregnancy; Kerry also figures it out. Mark and Elizabeth draw closer. Lucy tells Carter about her Ritalin addiction. "FBI agents" bring in a shot stripper.

Greene's daughter comes to live with him and Corday. Carter and Abby become more intimate. Chen must prove her skills while saving a baby. Weaver terminates Malucci after witnessing him having sex in an ambulance.

Amanda Lee's obsession with Dr. Greene comes to a head when Mark inadvertantly digs up old med school records damaging to her career. Carter tries to save Lucy from Edson's advances. Peter treats Dr. Parks' grandchild, who interprets for her deaf mother and grandmother. Police officer Reggie Moore asks Jeanie out. Kerry receives a call from someone claiming to be her mother. Doug receives a job offer from Portland.

Doug faces possible criminal charges after Ricky Abbott dies when Ross bypasses system lockouts to enable Joi to give Ricky a lethal dosage of dilaudin. Doug is delegated to desk duty, Carol's clinic is shut down for acquiring the P.C.A. machine for Ricky, and Greene and Weaver face future disciplinary action for not reporting Doug's tampering with the double blind study. Carter and Lucy discover a mutual attraction. Benton studies with a sign language instructor.

Shep and Raul bring a dozen malnourished and abandoned children into the ER, keeping everyone very busy. Shep has a run-in with Malik and Benton when he makes an off-handed racially insensitive remark. Carter's high from the admission of Mrs. Rubadoux to the study ends when she shows no signs of recovery. Jeanie and Carol clash when Jeanie receives a poor evaluation. Al asks Jeanie to give him another chance. Mark is served with divorce papers.

Corday rushes through a surgical procedure in order to take off on a romantic weekend with Greene. She is later called back to the hospital after her patient suffers complications. Abby's mother, Maggie, who suffers from bipolar disorder (manic-depressive) and refuses to take her medication, unexpectedly visits Abby at the hospital and wreaks havoc on Abby's life.

Mark, still upset over the loss of Jodi O'Brien, takes the night off but ends up in the ER anyway, albeit an hour late, when the new chief runs a drill at 2:00 a.m. Benton begins to realize his mother's future is not bright. Carter and Deb compete against each other. A small moon coinciding with the naturally heavy Saturday night traffic causes an exciting night.

Weaver reprimands Carter for doing a dangerous procedure without consulting Kovac. She also talks to Hathaway about Hathaway's lack of focus on the job. And while treating a 6-year-old patient involved in a minor car accident, Malucci and Cleo discover the girl has been sexually molested recently by her father.

Ross treats a 6-month-old recovering from methadone withdrawal. A televangelist and his wife, who's suffering from an infection, plan a broadcast from the ER. Del Amico's old boyfriend arrives, and Jeanie fears her health is rapidly declining.

Carter finally works up enough nerve to ask Del Amico out. Jeanie tries to help Scotty decide whether to undergo an experimental treatment and Benton takes unexpected action during an operation with Morgenstern.

In order to get her paitient to tell her the location of a missing body, Corday agrees to grant him a fatal wish. Kovac befriends two brothers. He tells Weaver that his wife and children died in the Bosnian war. Former medical student Deb Chen returns to County General as a resident, using her Chinese name, Jing-Mei Chen.

Dr. Nate Lennox, a former professor with ALS, is brought in as the progression of his disease is chronicled through his own flashbacks as he is treated by each of the doctors at one point. As Lennox wants to give up, Abby fights to convince him to keep on fighting.

Mark and Jennifer struggle to remain together as Mark has moved in with her in Milwaukee. Doug coaches Jake's little league team. Chloe's irresponsibility wears Susan down. Carter asks Benton to fill out a recommendation for the ER sub-I. Carol and Tag try to write their wedding vows; he becomes upset when Carol invites Diane Leeds, knowing that she'll bring Doug. Peter exhibits a growing attraction for Jeanie. Susan discovers what happened to Div when she spies his picture in a cabbie's dating service photo book. The staff discovers that Carter comes from a wealthy background.

The ER hosts roughly a dozen pregnant women when a sprinkler bursts in the maternity ward. Carter plays tour guide for the visiting surgical intern hopefuls before going through the interview himself. Benton tries to bring a hopeless patient back from the brink of death in a marathon surgery. Jerry tries to convince the others that basketball player Scottie Pippen visisted. Doug visits his father.

Carter has a difficult day when he has to identify a dead teenager and notify his parents. It doesn't help that he notifies the wrong family. Doug woos Carol, despite Taglieri's presence in her life. Benton clashes with brother-in-law Walt after he neglects family duties.

The ER staffers are in decidedly unfestive moods as Christmas arrives. Carol's spirits are lifted by a Santa-like patient. Mark is outraged when Jenn decides to stay in Milwaukee over Christmas. Benton and Carter score points with Vucelich when Carter convinces an older gentleman, Ruby, to include his wife in Vucelich's study. Mark gives a deposition in the O'Brien case. The death of a priest threatens to start a gang war. Weaver receives a surprise visit from an African friend. A Holocaust survivor, the victim of a carjacking, brings Chanukah to the ER.

Weaver and Susan's feud escalates to the point where Mark needs to step in and fix it. Benton is involved in a parking lot altercation, resulting in a broken hand and Carter replacing him in surgery. Mark cares for an abandoned elderly woman. Susan tries to juggle her work and care for Little Susie. Shep risks his life to bring in a gunshot victim.

Weaver rushes to the aid of her female life partner, Sandy Lopez, when the firefighter is severely injured while working and must now battle for her life. Frightened Weaver whispers hope to Sandy by reminding the victim of their newborn child.

Carter plays tour guide for Ruth Johnson, who was born in the hospital 100 years ago to the day, and her large family. Carol treats a boy who was hit by a car and tells a story of being chased, his friend being shot in the process. Peter observes Kotlowitz install a cochlear implant and decides to wait before scheduling an operation for Reese. Mark dines with Dr. Lee, new ER chief. Dr. Corday proposes radical changes in scheduling at an M&M conference, and later decides to break off her relationship with Benton.

A case of apparent spousal abuse is not what it seems. Deb outshines Carter after he is up all night preparing for a presentation. Peter informs Jackie he's hired a helper for his mother. First Kayson's reprimand against Susan is denied, then Susan has a chance to prove herself when Kayson is brought in as a patient. Dr. Ross meets Diane Leeds, of risk management, and her son Jake.

Weaver, Kovac, and the other doctors work frantically to try to save Jerry and a pregnant Abby, who were both critically injured during the shootout that left the ER in shambles. Meanwhile, Sam tries to escape from her ex-boyfriend and his criminal accomplices as they head north, but things quickly turn violent.

Abby's family nightmare continues as she and her mother Maggie search for Abby's missing brother Eric, who Abby suspects is suffering from serious mental problems. Meanwhile, Corday treats a family of patients who, while building a snowman, were severely injured after being struck by a truck driver.

Mark tries to find a way to tell Rachel about his impending divorce. Benton attends a banquet at Vucelich's home, with Jeanie as his date. Carter finally tells Mr. Rubadoux about his wife's terminal condition, making the man furious. Morganstern is admitted to the hospital after breaking a leg at a Scottish family reunion.

Ricky Abbott returns to the ER. Doug forges papers to allow Joi to treat Ricky at home. Corday decides to back out of the Romano sexual harassment investigation after he threatens to expose her relationship with Benton. Romano is later named Acting Chief of the ER. Dr. Greene treats a Nigerian janitor for back pain and impotency. Carol and the nurses watch a bunch of dogs when their owner is hospitalized. Carter diagnoses a med student with Hodgkin's disease. Kerry initiates a search for her biological parents.

Chen gives birth, but insists on breastfeeding the infant before she gives it to the adoptive parents. Greene and Corday consult a brain specialist in New York City who believes the tumor can be safely removed. Stressed and tired, Carter impulsively swallows two painkiller pills but intentionally vomits them. He confesses to Abby.

Weaver tries to save the life of a rape victim while Corday struggles with feelings of disdain as she is forced to save the rapist. Cleo treats a teenage alcoholic boy whose alcoholic mother refuses to recognize her problem or his.

Hathaway treats a rape victim. Walt brings Benton's mother to the ER with a sprained ankle. Carter shows his annoyance toward Benton and his stand-offish attitude. Mark calls in sick to spend time with his wife, leaving Doug as a hectic acting chief. Div shows signs of snapping, overreacting at the smallest provocation. The ER gets a new desk clerk, 'Bob'.

Greene tries to help Mobalage when he's about to be deported. Kerry tries to save a woman she believes is her birth mother. Hathaway decides to have Doug's child. Benton and Corday clash over an ER fellowship. Carter is in charge for the day, part of a requirement for applying for chief resident.

Benton decides to blow the whistle on Vucelich's unethical study methods, causing Vucelich to drop him from the study. Susan treats a street couple, one of whom has passed HIV to the other. Doug receives a visit from his estranged father. Carter spreads rumors about an affair between Mark and Susan. Mark buys a motorcycle. Prostitute Loretta has cervical cancer.

Gates and Morris tend to an elderly man who was assaulted on the street. Sam 's sister shows up unexpectedly. Brenner and Dubenko clash while treating a mother thought to have late-stage cancer. Dr. Morgenstern returns to the ER to assist a former mentor who is seriously ill.

Even though he suffers from intense pain due to his stabbing injuries, Carter returns to work and prescribes a controversial procedure for a suicidal patient. Greene tries to convince his father to undergo cancer treatment.

A 31-year-old security guard is brought in suffering from severe chemical burns, and a 21-year-old man is wheeled in after falling 75 feet into a river. Meanwhile, Benton is upset that Carla's boyfriend is part of Reese's baptism.

Benton and Langworthy interview for the Starzl fellowship. A drunk Chloe throws a tantrum in the hospital. Benton saves a man with a throat wound, earning Morganstern's praise. Carter has a good day, winning a bottle of champagne and getting three leads on apartments. Carol has second thoughts about moving in with Tag after a spontaneous kiss with Doug.

Susan institutes extra precautions in case Chloe tries to reclaim Little Susie. Mark changes his look, growing a goatee and wearing contact lenses. Carol and Jeanie square off over the care of a transient. Carter celebrates when he receives his residency match, putting his patient and his job at risk. Shep, still suffering from Raul's death, is surly with new parter Reilly. Benton and Ross have differences when Peter discloses a critical mistake made by Doug, raising animosity between the two.

Carol's pregnancy becomes public knowledge as she learns that she's having twins. Lucy has problems trying to go off Ritalin. Peter learns Carla plans to move to Germany. Kerry finds an abandoned youngster and brings him to the ER. Mark and Elizabeth discuss their relationship. Jeanie and Reggie draw closer again.

Carter gets his first patient...and loses him. Susan's feud with Kerry Weaver intensifies when Weaver demands all of Susan's procedures be cleared with her. Chloe abandons Little Susie again for a lucrative career in the flea market business. Carol finishes her paramedic recertification by picking up a very overweight, lethargic man. Shep hits on Carol. Jeanie ends her relationship with Benton. Wendy conducts interviews with various ER staffers for an article on Dr. Greene. Dr. Ross cares for a four-year-old Asian boy with AIDS.

Tests reveal that Greene has a brain tumor, but he hides the news from Corday. Corday finds out that she is being sued for malpractice. She also reveals to Greene that she is pregnant. Abby's mother refuses to leave. Abby expresses resentment over her difficult childhood to her mother but resignedly brings her home for Thanksgiving dinner.

Speculation runs through the ER, on a very hectic day, about Randi's possible criminal history. Mark faces an ethical dilemma when he has to decide whether to report yet another of Doug Ross's indiscretions--Doug slept with med student Harper Tracy. Carter becomes upset when Harper confesses this to him. Carol meets with a mobile notary to finish the paperwork to purchase a house. Bernstein informs Doug that he need to look for other employment. Benton is visibly upset when Jeanie begins work in the ER as a physician's assistant.

Maggie's emotional instability worsens. She refuses her medication, becomes combative and flees the hospital. Abby finds solace with Kovac. The gang member girlfriend of Benton's deceased nephew knows who killed him and that he was hated for his antigang stance.

Carter is overwhelmed by patients from a rock concert riot. Benton's former girlfriend is killed in a car accident. Newly promoted to chief resident, Chen panics and misdiagnoses a patient. Kovac angers Abby by flirting with a waitress.

The ER treats victims of a gang shootout. Carter arrives late and unprepared for his new position. Mark learns all about being an attending, including senior staff's habit of bad-mouthing the residents, particularly Doug Ross. Mark hires a new chief resident, Kerry Weaver. New third year med students arrive to complete their ER rotation.

Doug jeopardizes future federal grants for the entire ER when he breaks a double blind study by giving a sample drug to an ailing patient. Doyle lodges a sexual harassment complaint against Romano, hoping Dr. Corday will lend support. Lucy begins her surgery rotation under Benton's tutelage. The two of them treat a man claiming to be 140-years-old. Mark declines to proceed in the NASA program. Carol questions Lynette's intentions when she hosts a women's health clinic for African American women only. Mark goes to bat for Pickman when she inadvertently leaves a severely injured man at an accident scene.

Chaz, now a med student, begins his ER rotation. Morris takes him under his wing and shows him some risky procedures, endangering a patient and raising Banfield's ire. Neela becomes upset when Banfield questions her authority and skills in front of her intern. Gates invites Sam and Alex to move in with him and Sarah.

The rainy night brings in diverse patients including a mother involved in a car accident with her baby, a man with a satisfaction facilitator, and a comatose patient who suddenly wakes up. Also, Sam steps up to Eve and her strict ways and Jerry gets struck by lightening!

A package for Morris from his deceased father is delivered to the ER. Sam has some anxiety over Alex being removed from the ventilator. A woman with a high-risk pregnancy worries that she will be deported. An old friend returns to celebrate the holidays.

A power outage strikes on an unusually hot day, bringing nursing home patients suffering from hyperthermia to the ER. Abby and Pratt disagree about diagnostic tests for a fussy baby. Morris and Pratt get their board results, and the ER staff celebrates at Ike's. Moretti and Abby's interactions intensify, and Abby finds herself at a dark and frightening crossroads.

When a drug deal goes bad, two brothers sustain serious injuries and are brought to the ER. Tensions continue between Gates and Sam, coming to a head when Tony is the last to know Alex is about to be released from the hospital. Neela has to tell a young girl with sickle cell anemia that she must have an operation, and the case leads her to consider specializing in pediatric surgery. A feisty patient takes Morris into her confidence. Banfield ponders her choices about expanding her family.

Morris is named the new chief resident, which makes nobody really happy, except Morris. Meanwhile Luka and Sam are having communication problems, Carter gets a promotion Susan really wanted and Ray finds out a 14-year old who always comes in for free drugs has been raped.

Dr. Banfield defends herself during a mugging. Dubenko returns to work, due in no small part to Brenner's organized protests. A young gymnast comes into the ER with injuries consistent with a fall, but Banfield and Gates each think a different family member may actually be to blame. Sarah neglects to ask Gates's permission before getting her tongue pierced.

Confident second-year resident Pratt wants to prove his abilities when he works the graveyard shift (11 p.m. to 7 a.m.), but his heroics sometimes backfire. Pratt shows contempt for a man, Ed Gamble, who presents no symptoms of disease but temporarily loses his speech.

Pratt and a new doctor on the scene disagree on how to teach the interns. Gates treats a young woman with serious heart problems. Abby heads to Croatia, and ponders whether and how to tell Luka about her unfortunate choices. Sam discovers that Julia has moved on in more ways than one.

Kovac and Gates deal with a hopeless father whose son succumbs to heart failure; Pratt tries to resolve the tension between him and his brother; an Armenian man tries to be a good samaritan but ends up crashing near the ER; Abby sneaks in baby Joe when she worries his sickness may be worse than it seems; Also, Sam injures the instructor of a self-defense seminar.

As the new director of diversity, Benton studies medical school applications and discovers that his own academic record did not qualify him--he was admitted because of affirmative action. Weaver feels uncomfortable amongst Legaspi's lesbian friends. Carter treats an unvaccinated child who contracted measles.

Pratt departs for Africa with attitude to spare but makes his first contact with harsh reality before the plane lands. Abby senses something is not what is seems when she treats a 12-year-old and her grandmother, then differs with Luka over the best course of action. A prisoner is brought to the ER with what everyone thinks is a fake case of appendicitis. Morris is dressed, and ready, to impress, but Albright’s not. It’s time for Kerry to return to work and Clemente doesn’t know when it’s time to leave.

It's time for changes at the ER when Anspaugh makes an unpopular decision. Abby has old demons to fight with, which distance her from friends and family. Even Luka seems to be at a loss to help Abby. Love is in the air when a secret romance blooms between two doctors.

A camera crew shooting footage for a documentary interviews members of the ER staff. Detective Claudia Diaz is brought in, critically injured with gunshot wounds. Neela laments the lack of communication between her and Brenner. Sam struggles to reconcile with her mother. Carter's condition worsens quite suddenly.

Neela's aortic rupture patient is in need of yet another follow up surgery, and they are starting to take a toll on her. Morris talks with a shrink about his experience with the jewelery thieves. Abby needs to make a tough decision when a new opportunity is presented to her.

Everyone in the ER is trying to cope with the loss of their colleague. The staff feels defensive toward the new Chief and her tough disposition. Gates and the new interns treat a bio terrorist who has a lethal secret that endangers them all. Neela makes a great effort to get Dubenko back on the surgery staff, and gets help from an unexpected source.

A mysterious illness leaves little hope when a group of homeless kids enter the ER and one of them believes that Neela is a guardian angel in blue; Abby and Kovac clash over a possible case of domestic abuse; Pratt makes a shocking discovery about his brother, and Weaver is unexpectedly called into action when her television appearance becomes a real emergency.

Neela starts a new job in the emergency room after working at the convenience store near the hospital. On Neela's first day, Pratt expects the interns, Abby, Ray and Neela, to take on a large patient load during their shifts. Pratt turns processing the patients into a competition, in which Ray is clearly going to be the winner.

Neela's short visit in Ortho turns into a game of hockey. Bettina wants to take her relationship with Pratt to the next level, but Pratt is not keen on the idea. Gates and Sam disagree over a patient. Julia provides some spiritual guidance in order to ease a prison doctor's bad conscience.

Weaver returns to the emergency room after a self-imposed sabbatical of three weeks, wondering how her newfound lesbian identity will affect her workplace relationships. Having purposely allowed a mass murderer to die, Greene must keep the secret amidst the scrutiny of his superiors.

When Luka answers a call for help, he discovers not everyone is pleased. Will he honor his commitment, or ask a colleague to step in for him? Abby and Morris wrestle with the strange case of a car crash victim. Having made a change in her life, Sam finds herself enjoying a few new perks. Neela has unexpected visitors, with even more unexpected news.

In the Sudan, Carter and a colleague struggle to save a woman who was raped by a band of militants. Back in the ER, Clemente asks to return to work after the shooting incident, but Kovac refuses. Meanwhile, Neela and Pratt have a work dispute, and, in a related incident, K.J.'s father shows up again in the ER.

Neela, worn out after being on shift for over 24 hours, has to make a quick decision regarding an accident victim's torn aorta. Sarah's grandparents are in town, and Hank is rushed to the ER after collapsing during an outing. Gates tries to convey to Sam that his feelings for her are serious.

A new attending, Dr. Victor Clemente, comes aboard and quickly makes a stir on the ER. Abby's breast cancer patient convinces her to take a long awaited test. Luka befriends a young woman who awakes from a six-year coma. Also, Weaver shows Clemente who runs the ER.

Curtis Ames, a carpenter who suffered a stroke under Kovac's care, sues him for malpractice. Kovac and Ames square off in court as each man's recollections of Ames' treatment are recounted via testimony and flashbacks. Meanwhile, Abby returns to work and must adjust to the dramatic changes in her life, and Pratt's early morning trip to the barbershop results in a new awareness of community need. Also, Abby and Pratt try an unconventional method for treating a heart patient and Neela tries a risky procedure which doesn't sit well with her chief.

Gallant impulsively asks Neela to marry her that exact day, she says I do but soon gets cold feet. Morris stands up to Weaver on a patients course of treatment. Luka, Sam and Clemente treat a boy who contracted HIV from his mother. Also, Abby and Luka redefine their relationship and Luka is named the new Chief of Emergency Medicine.

As a snowstorm hits Chicago, Sam's son Alex crashes a car and ends up in critical condition in the ER. Neela gives a deposition in the malpractice suit against her. Banfield and Morris are both at a medical conference in Omaha, and when the snow cancels all flights out, they share a memorable and surprising evening.

Sam gets frustrated with Gates when he gets obsessed with finding a homeless war hero. Neela is upset at her intern after he gets the entire surgery department into a lawsuit. A husband and wife come into the ER after someone tried to burn down their home. Brenner loses his cool with a patient and it gets physical.

Much to Ray's dislike, a surrogate mother in labor doesn't want to have a C-section and endangers the life of the baby. Meanwhile, Sam tells Luka she and Alex are moving out. Pratt meets his half-brother and -sister, and Abby makes a difficult decision about a young boy.

Pratt's half-brother tries to get him to make ends meet with his estranged father. Clemente treats an infant chimpanzee and involves Abby and Neela on the secret case. Eve promotes Sam and her first tasks is to fire a beloved nurse.

Carter returns to County General to hearty welcomes. Although Abby is shocked to learn that Carter's beautiful African girlfriend, Kem, is already pregnant with Carter's child, Abby has moved on with her life as well, going back to medical school.

In 12 hours, the ER will shut down. As Kovac is under pressure to take care of the patients before the final hours, he makes a pivotal decision about his future. Meanwhile, Sam befriends a photojournalist who returns only this time she's terminally ill; Pratt is concerned when his brother ends up in the ER drunk; Morris confronts Gates when he ignores his orders and angrily sends him home while Gates tries to defend his actions.

A belligerent young man with the flu turns out to be more than he seems, and presents a challenge to Morris and Sam when he refuses treatment. Abby's chance encounter with Curtis Ames leaves Kovac uneasy. Meanwhile, Pratt discovers a local church's risky drug exchange program, Neela and Gates square off, and Weaver gets an interesting offer.

Abby and Luka desperately try to keep a young woman brought into the ER with stab wounds to the neck alive. As her condition begins to worsen, Clemente steps in and tries a risky procedure on the girl in order to save her life. Meanwhile, Neela pulls an all-nighter in preparation for a speech at a surgeon's convention, Ray treats a man claiming to have swallowed a bottle of pills, and Sam decides to take a part-time job with Richard to help her with childcare expenses.

Abby and Kovac discover both the joys and difficulties of raising a newborn; Morris is wrongfully accused of being a child molester; Pratt has his trial-by-fire when he has to handle the ER alone, juggling multiple traumas, teaching duties and a troublesome intern. Neela continues to be the target of her difficult supervisor, and Sam discovers her sons latest extra-curricular activity.

Season Finale: Luka postpones his honeymoon, leaving Abby, Joe and the ER behind to begin a different journey. Meanwhile, it's Moretti's first day as Chief of Emergency Medicine, and everyone feels the effects of his style, especially Pratt and Morris. Neela learns of Ray's fate, then joins an anti-war rally and finds herself in a dangerous situation. Gates faces a crisis on the home front.

Moretti reassigns Gates back to the ER and treats a couple involved in a car accident. Morris prepares to take his written board exams. Neela is assigned a young genius intern. Kovac plans to extend his stay in Croatia while Abby struggles with single parenthood.

ER's 300th episode finds Luka and Abby hurriedly preparing to travel to Croatia after Luka's father passes away. Luka confronts Abby about the estrangement between them, and she eventually reaches out and asks for his help. A man rushes to the ER when his wife is seriously injured in a car accident, and finds someone very unexpected there with her. Julia holds a service to bless the ER and remember the patients that have been lost through the years.

Pratt struggles to diagnose a woman who suffers mysterious chronic seizures. An attractive woman, Campbell, informally accuses flirtatious Pratt of sexual harassment. Abby ponders how to get her contentious patients' attention during her psychiatric department rotation.

Abby is back from rehab and finds herself the object of scrutiny. She confesses to Pratt that Luka might stay in Croatia longer than planned. Harold seems to have won over Neela's cousin. Multiple victims from a fire fill the ER.

Kovac and Gates find themselves with a moral dilemma when a woman comes into the ER with acute liver failure; Neela finds herself questioning what is right when Manish decides to give up a kidney to a complete stranger. Meanwhile, Ray fights to get to the bottom of a cheerleaders accidental fall; Abby gets a prediction for her future; and Alex's troubles continue to intrude on Sam's work life.

Susan visits a psychiatrist to cope with the loss of Little Susie. Jeanie's estranged husband Al checks in the ER complaining of flu-like symptoms, which turn out to be caused by HIV. Shep expects Carol to back his version of events during an official investigation of his behavior. Loretta takes a turn for the worse. Doug discovers that his father has disappeared with a LOT of Karen's money.

A blizzard strands a family in the snow and Abby and Pratt quickly try to save the family. A gang shooting challenges Morris and Pratt. Meanwhile, Kovac and Abby begin making wedding plans, but their engagement might not be very secret; Gates struggles with the reappearance of his father and the possibility of losing Sarah; and Neela becomes jealous when Dubenko brings in a new surgical intern.

Morris and Pratt cram for their medical boards when Morretti brings in a new attending physician to help with the load. Sam and Abby work on an attention-hungry patient who comes into the ER with elusive symptoms.

Dr. Kevin Moretti, an ICU specialist bent on change, joins the ER team. Change comes elsewhere as Luka and Abby adjust to being husband and wife, Pratt tries to be a new man to his lady friend, Morris and Hope take things to the next level, and Ray goes missing. Later on, Luka gets a troubling phone call.

Kovac and Gates treat a girl who appears to have been assaulted. When the police are no help with Ames, Kovac decides to confront the problem himself; Morris and other doctors work on a patient with an ice pick in his ear. Meanwhile, Ray tries to keep his new relationship a secret and Pratt can't fully deal when his half-brother officially comes out. Also, a new male nurse arrives.

Abby and Sam try to treat an obnoxious, aspiring comedian with mysterious symptoms; Pratt must defend his actions in front of the medical board; Neela scrubs in on a kidney donor transplant; and Morris, as the lone attending, must run a busy ER. Also, Kovac gets a surprising proposal from Abby.

There's been a jewelry robbery in town, and Neela finds out that one of her patients might have had something to do with it. Pratt makes an effort to save his relationship with Bettina, and Abby worries about her marriage, sensing that Luka may have given up on it.

Corday's ordeal, caused by the recent infection-related deaths of several of her patients, worsens when she is closely observed by a stern taskmaster. Corday is outraged when a county investigator accuses her of deliberately euthanizing the patients, who all happened to be elderly.

Corday clashes with new surgical resident Paul Nathan regarding his intervention into the treatment of a sickly young woman, Alison, who has signed a "do not resuscitate" order. Abby wonders about the erratic behavior of her visiting brother Eric, and feels conflicted over a nurse's official complaint against Kovac, Abby's former lover. Meanwhile, Pratt comforts Chen after a patient threatens her, and Corday suspects that an unconscious, 14-year-old female patient has been sexually assaulted.

It's Halloween night, and the interns continue to be paired with the residents. Gates's teaching methods with Daria, and her responses, belittle Sam. A school fight results in a stabbing and a nose that won't stop bleeding, with Brenner treating the victims and being deeply affected by the truth behind their confrontation. The staff, especially Neela, are enthusiastic about a surprise visitor. Gates gets locked in a maintenance area with a quiet young boy.

Lewis faces a hectic first day back at County General. Benton and Roger become frantic when they can't locate Reese. Carter's grandmother is brought to the emergency room. Carter and Abby deal with inept medical students.

Ray helps an old friend escape from her abusive father. Dubenko volunteers in the ER but can't seem to handle a slow day. Abby and Kovac go baby shopping, while Neela gets unexpected and upsetting news from Gallant.

Carter returns from Africa, going straight to Abby's bedside. Her response to seeing him is to ask for her key back. She is very chilly towards him all day until new med student Neela Rasgotra answers a phone call for Carter. The message: Luka is dead. Carter decides to go back to the Congo to bring the body back. Neela has a tough first day in the ER, earning Chen's ire after Pratt flirts with her. Gallant, now a full-fledged doctor, helps to show her the ropes.

Carter, Pratt, Kovac and Abby are dealing with a woman and her three children who've jumped from a three floor apartment trying to escape from the father. Meanwhile Dr. Lewis becomes Chief of Emergency Medicine, Howard quits his internship and Dr. Corday is facing dismissal.

Thanksgiving at County is quiet, with the normal number of routine (or nearly so) emergencies. But Abby makes up for the lack of excitement while returning to the hospital as the doctor on a helicopter transport.

Two wounded police auxiliary officers present challenges in the ER. Neela settles in with Abby as she recovers, while Pratt and Bettina consider their relationship. Gates tries to get a patient on a drug trial, with Dubenko's help. And Morris is in a funk that not even a pretty woman can help.

Abby and Carter travel to Oklahoma to rescue Abby's mentally ill mother and bring her back to Chicago. In Chicago, Maggie suffers from a sleeping pills overdose. At County General, Kovac frantically revives her. Benton treats a college student injured in a fraternity prank.

It's Sam's birthday, but she finds it hard to be away from her son Alex. Meanwhile, Sam meets a photographer taking pictures of a terminal patient and she gives Sam a new perspective on life. Dubenko's new surgical intern unsettles Neela during a trauma; Gates is shadowed by a new and nerdy intern and later must tell Sarah the truth that he may be her biological father. Also, Morris and Hope annoy Kovac and Abby when they try to help with their wedding preparations.

It's Valentine's Day. Dr. John Carter is back at the County. Brenner and Neela are getting closer. Dr. Banfield is having a hard time trying to have a baby. And Puck and mushrooms may not be a good combination.

Weaver cares for a Katrina survivor who's reluctant to having surgery on her foot; budget cuts force Luka to make a difficult personnel decision. Also, Gates' home life intrudes on the ER; and Pratt and Hope are shaken after a patient in their care dies needlessly.

Kovac reacts negatively when he sees Abby giving extra attention to a patient; Ray and Gates clash over a patient, pinning Neela in the middle; and Ben takes things to the next level with Sam. Meanwhile, Pratt is under investigation and Weaver says a final goodbye to the ER.

It's Christmas in the ER. A homeless boy sends Gates and Ray on a mission. Meanwhile, in the ER, Neela oversees an unusual kidney transplant case; Sam takes a stand when a patient is dumped in an alley by another hospital; and Morris plays Santa for a special girl and learns the meaning of Christmas.

Morris streets a patient without getting a psych consult, and the guy steals a tank and heads for County. Gillian is visiting Luka, and Sam's not happy about it. Luka and Sam make up by the end of the day though. A 13-year-old boy has chlamydia. Frank has a heart attack. Corday plays the dating game, going out with two men.