After Hughes's attack on Devlin, Glynn withdraws from the race. Alvarez is still on the loose. Supreme Allah gets an unwanted surprise.

Beecher is released from the hole and Schillinger is left eyeless and weak. A riot breaks out after two white punks get into a fight over checkers. Frustration, sexuality, hate, revenge, racism all rear their ugly heads, causing the violence to escalate.

In the Season Four finale, Hill discovers where his true allegiances lie. Redding's plot to use the Colonel against Morales has an unexpected outcome. Cloutier runs into trouble from his church on the outside and his parishioners in Oz. White gets a little too close to McManus. Beecher's agony about his parole hearing leads to a shocking climax.

Wittlesey is transferred to Gen Pop and replaced by Karl Metzger, a Nazi. Mack and another Aryan try to escape through Busmalis and Rebadow's tunnel but the tunnel collapses and kills the two Aryans. Hill gets the idea of escaping Oz by hiding in a coffin. Sippel re-enters Oz because he can't deal with life on the outside, but Schillinger crucifies him -- literally. Alvarez gouges out Rivera's eyes and is put in solitary for life. Needing a blood transfusion for Rivera, Dr. Nathan finds that only O'Reily has the same blood type; he agrees to donate in exchange for getting his brother Cyril near him. Keller and Schillinger reveal their sordid plan of deceit to Beecher while breakingv both his arms and legs. Fortune teller Kipkemei Jara gives Adebisi hope of a new life; but he is murdered by Wangler on orders from Antonio Nappa. The grief this causes Adebisi lands him in the psych ward. Said is pardoned by Governor Devlin, but refuses choosing to return to Em City instead.

A recovered Saïd ostracizes Mershah for turning his back on him when he was dying—and orders the rest of the Muslims to do the same. Impressed by Saïd's power, Groves makes a deadly decision in his honor. Meanwhile, Beecher, transformed by prison life, finally gets revenge on Schillinger.

The lockdown ends. After Hamid Khan's body is taken off life support, the Muslim's choose Arif to lead them. Meanwhile, Cyril's having nightmares about delivering the fatal blow to Khan in the boxing match. Ryan asks Sister Pete to intervene. Murphy makes a suggestion to help ease some of the strain in solitary after another inmate commits suicide. Father Mukada plants an inventive idea in Beecher's head on how to deal with Schillinger. Shirley Bellinger returns awaiting her date with the noose. New inmate Mobay, arrives to Oz and his cellmate Hill is immediately suspicious. Gov. Devlin invites Glynn to be his running mate in the Gov's re-election bid. McManus gets an update on Wittlesey, who hasn't returned from vacation and a shootout in Oz results in four deaths.

O'Reily regrets getting Cyril involved with the trial drug when it starts taking effect. Meanwhile, Giles's request for an unusual method of execution creates controversy and the Chinese refugees are deported...but not before plotting revenge on Morales.

Robson returns from solitary to discover he's been kicked out of the "Brotherhood" and moved to another cell. McManus tells Glynn he'll write a letter supporting Alvarez's bid for parole. Problem is, Alvarez attacks one of the parole board members and gets thrown back into solitary. Dr. Nathan's guilt worsens as Chucky slips into a coma from the septic infection. Schillinger tells new inmate Cutler he has to kill a black inmate to join the "Brotherhood" and Cutler selects Said as his victim. White's gets this information and goes to protect Said only they get into a tussle and Cutler almost dies. Rebadow gets to go see his dying grandson only to have to return later for the boy's funeral. Busmalis gets a letter from Norma who wants to visit. She does and brings surprising news. Beecher moves to make a confession during the interaction session. The result? Schillinger gets convicted of rape and is transferred to solitary indefinitely. Father Meehan touches a nerve with Ryan and forces him to acknowledge a childhood incident that scarred Ryan for life. A stabbing intended for Redding, claims an innocent inmate instead.

Sister Pete's anger is roused and forces her to confession. Wangler and Adebisi register a complaint to the Warden. Yet another inmate meets with demise. Bellinger enlists McManus' help. Glynn and Hughes have an important conversation. Adebisi begins sowing seeds of discontent and a fight erupts in the gym resulting in a lockdown.

In addition to the name change to "Oswald State Correctional Facility," more changes abound. Newbies Coyle, Kahn, and Ricardo arrive and partner up with Wangler, Said, and Hernandez respectively. Adebisi's "recovery" prompts a return. Clayton Hughes, son of a past Oz guard who came through the ranks with Glynn, asks Glynn to hire him. Meanwhile new Officer Howell, gets friendly with McManus. A managed health care company takes over Oz's infirmary, to Dr. Nathan's disgust and Alvarez's detriment. Cyril O'Reily still has nightmares about being raped by Schillinger and Ryan schemes on revenge. Said develops an unlikely alliance as he starts a hunger fast in response to McManus rejecting his request for food in his cell during his holy season. Keller confesses his part in setting up Beecher and is immediately taken into protective custody. Beecher gets some oh-so-sweet revenge.

Schillinger has a disappointing visit with his "hero", Mayor Loewen. Glynn has to face up to the truth when Oz loses its first prisoner to toxic poisoning. Down in solitary, Officer Brass gets some quality one-on-one time with Morales. Cyril undergoes a round of unusual therapy, and Said gets more than he bargained for in leading the Muslims into a new business venture.

Things get a bit lively on death row after Shirley Bellinger's execution-- Miles begins painting a self-portrait, Ginzburg's health deteriorates from AIDS and Deyell severely injures himself. Mobay's ordered to kill someone as a final test of his loyalty and a new prisoner, whom Mobay's familiar with, makes the perfect victim. A call stirs McManus' emotions again. New inmate Supreme Allah arrives creating tension and uneasiness for Arif. On his way to his son's funeral, Beecher asks Keller an intimate question. A changed Rebadow asks for permission from Morales to kill again. After a fight with the gangsters, Cyril's put on heavier sedatives. For Ryan O'Reilly, he gets the cell phone after ratting to Hoyt and he also meets Dr. Nathan's attacker.

The kidnapping of Beecher's children has everyone upset and Beecher inconsolable. Schillinger gets questioned and of course, claims to know nothing about the deed. Beecher decides to initiate his own investigation. Soon after, a package with horrendous contents arrives for Beecher. Meanwhile, Oz prepares for Shirley Bellinger's hanging as the death penalty protests continue. A visit from the Cardinal creates mixed feelings for Sister Pete and Father Ray. Said announces good and bad news in the state's decision for the inmates. Another Rebadow prediction comes chillingly true. O'Reily's still searching for that elusive cell phone and Dr. Nathan asks Glynn for permission to return to work earlier than expected.

The hack ain't comin' back, and everyone's trying to figure out who did the deed; especially Schillinger and Said. McManus hires a new officer Sean Murphy who's also a friend of Tim's. Despite Glynn's reservations, an inmate boxing program is is created and inmates get psyched for the competition. While closely shaving Hill, Coyle gives the gruesome details of his crime, which include the death of an infant and the discovery of indisputable evidence to his claim. Disgusted, Hill decides Coyle should pay and gives the info to Warden Glynn. Adebisi gets approved to work in the AIDS ward. While Howell and Wittelsey converse about McManus, he appears with bad news for Wittelsey. Meanwhile, Schillinger's son Andy has been arrested and is due to arrive to Oz any day. Keller, stir-crazy from being in protective custody, goes back to Em City with painful results. Alvarez begins deteriorating now that his medication has been eliminated.

Ryan and Howell get frisky. After leaving the hole and apologizing to Busmalis for the stabbing Rebadow suffers an attack due to a brain tumor. Busmalis reacts by doing what he does best--start another tunnel. Unbeknownst to the doctors and everyone else, Cyril's recovering psychologically more than he can actually show. Arif confesses to Said about his own demons and asks for forgiveness and help. Said plots with McManus to end Querns' and Adebisi's control. Hank Schillinger beats the kidnapping rap and once Beecher finds out, he plots with Pancamo for revenge. After Keller reveals his plot to kill him, Eli Zabitz asks Schillinger for protection. Schillinger agrees but sends Robson to eliminate Zabitz instead. Hughes, now raging beyond sensibility, makes an attempt on Devlin's life at a press conference. Keller and Father Ray have an intense discussion about Beecher.

With a new day breaking, Officer Howell makes a gruesome discovery. Dr. Nathan takes action against medical official Garvey. Ricardo and Hughes have a brief confrontation that results in a reprimand. Said's attorney brings good news and a special delivery. Richie Hanlon explains to Shirley Bellinger why he's on death row. New prisoner Stanislofsky joins the fold. Each group in Oz prepares their boxer for upcoming matches. Hill returns from testifying against Coyle, and the jury's still out as to whether or not that was the smartest move. Said solicits assistance from Nappa, Schillinger and Guerra. Nappa turns over control to Pancamo after discovering he has a debilitating illness.

Mobay has his first meeting with Adebisi. Glynn fires McManus after Tim makes a foolish outburst during the slain CO's memorial service. Sister Pete still wrestles with ending her service as a nun. Beecher's dad pays a visit and gives an update. Schillinger is visited by his other son, Hank. Said's decision to help Cramer secure a new trial is met with strong opposition by the Muslims. Poet grieves and ponders his next move now that Wangler and Pierce are dead. O'Reily's plan to get the cell phone backfires and results in another inmate's death. Bellinger returns to Oz to await her impending execution.

As friction grows in the wake of increasing deaths, Schibetta, Saïd, and Keane are brought together by Glynn, who tells them to keep their respective groups quiet or else he'll lock the prison down. The tension increases following a visit from Governor Devlin, who was responsible for the ban on smoking and conjugal visits.

Alvarez and Guerra come up with a new way to settle their beef -- Guerra will stab Alvarez in the shoulder without killing him. Morales questions Guerra's decision to do this while he attempts to grieve for his sister. Rebadow gets more bad news about his grandson which prompts him to search for alternatives. Montgomery asks for more hush money from Ryan so Ryan devises a plan to have Montgomery eliminated. Officer Brass returns to Oz to get facts on who attacked him. Ellie O'Connor arrives as the Governor's liaison to Oz only past memories of her failed marriage to McManus return. Schibetta returns and Schillinger shanks Pancamo after learning that he had Hank killed. McManus makes an offer to Said and White to hopefully curb White's erratic and sometimes bizarre behavior. Ryan's mom, Suzanne Fitzgerald comes to Oz to instruct inmates in performance arts.

Said returns from the hole ready to apologize to White. The inmate variety show takes shape with Busmalis as MC and White the featured performer. Robson's painful teeth force him to the dentist, something he secretly fears. The dentist recommends gum replacement surgery. Alvarez wants to give his dog to Rivera the Oz guard he blinded. Cyril's trial looms and Ryan's worried. Redding continues to search for culprit that gave Hill the drugs. Poet, in an attempt to hide the truth from Redding convinces Busmalis to tell Redding that one of the Italians did the deed. This results in Redding having DeSantos poisoned. Chucky's condition worsens and out of fear, he summons Sister Peter for spiritual help. Meanwhile, Sister Pete starts looking for Guenzel's attackers only the 3 who know (Said, Beecher, Schillinger) refuse to divulge.

Guerra kills Alvarez's new follower and the guilt surrounding it forces Alvarez to make a confession to Mukada. Alvarez, Hill and Penders sign up for a seeing-eye dog-training program. Dr. Nathan attacks a patient while having a flashback of her rape. Cyril shanks and kills Li Chien, which gets Cyril sent to solitary and Ryan sent to the cage. During an interaction session Beecher attacks Schillinger after Schillinger denies ever raping him. Redding asks Glynn for control of the kitchen. Hill's grief over his dead mother and divorce from his wife send him back to drugs happily supplied by Poet. Beecher's new podmate is the son of a prominent family Beecher knew well. Because of that, Beecher decides to protect him from the Aryans at all costs.

The unexpected arrival of Mayor Wilson Loewen at Oz spurs an ironic turn involving Schillinger and Beecher. Meanwhile, Dr. Nathan discovers why solitary inmates are getting sick; a new business plan within Oz inspires Redding; Schibetta looks to puts a curse on the O'Reily family; and some Death Row prisoners get a bang out of a magazine photo shoot.

O'Reily is in for a surprise when a visitor reveals the truth about his past, while Cyril faces trouble for his difficult behavior. Meanwhile, Morales and Redding lay out plans that could lead to all-out war in Em City.

Glynn receives some good and bad news on the toxic-poisoning case. Meanwhile, Rebadow's relationship with Stella hits a snag; Keller and Beecher work out a mutually beneficial arrangement; Poet and Redding nearly come to blows; Hoyt is transferred from Death Row; and Robson finally gets some redemption.

Everyone has a different opinion of new inmate Idzik; Alvarez receives shocking news; Redding's attempts at reform continue; Murphy makes a confession to Glynn; Morales'(David Zayas) medical suspicions are confirmed; and Beecher's devotion to Keller leads him into a perilous position.

Redding discovers that Busmalis lied about DeSantos. Furious, he confronts Morales and the confrontation gets the two of them thrown in the hole. Cyril gets convicted of the murder and Ryan tells the attorney not to appeal. Meanwhile Sister Pete, Father Meehan and Suzanne Fitzgerald meet to devise another plan in Cyril's defense. Rebadow fumes over not getting the lottery money. Mc Manus' offer to search Oz's databases reveals an inmate with the same blood history as Rebadow's grandson. Rebadow meets the man only to be rejected by him. The rumor of Robson's replacement gums coming from a black patient prompts Schillinger to consult with Aryan Nation leader. The result? Robson gets banned from the Aryans.

Schilinger enlists Said to get him out of jail, but Said backs out. McManus decides not to incriminate Wittlesey in Ross's death. A recovered Schibetta edures more pain after being raped by Adebisi. Meanwhile, Alvarez is bumped out of the Latino power seat by Raoul Hernandez, a.k.a. El Cid. New inmate Jiggy Walker claims he was Gov. Devlin's personal crack dealer. The two go head-to-head in the media before Walker is discredited and sent to genpop. Reimondo finds out that Giles murdered the man who killed her husband and Dr. Nathan confronts O'Reily about her husband's death. Schillinger's plan to destroy Beecher approaches fruition when Beecher falls in love with Keller.

Said and Arif go to Warden Glynn about Lalar's murder. Angry and full of rage, Said then confronts White about passing drugs. Unsatisfied with White's response, Said beats White severely, which gets Said thrown in the hole. Chucky Pancamo's condition worsens. On orders from Schillinger, Winthrop gets into a fight with Guenzel. Schillinger goes to with a deal, he'll let Beecher work for him delivering mail to Keller if Beecher has Guenzel transferred to Gen Pop so Schillinger can have him. Keller discovers the feds have compelling evidence linking him to one of the past murders. Meanwhile, Howell makes her move on Keller, Rebadow's ship comes in...for someone else and Hill becomes gravely ill.

With Schibetta and the prison brass in a race to uncover Ortolani's killer (for very different reasons), we see how inmates react to visits from both their wives and, in one case, family members who are also in prison.

At the bi-annual review of solitary prisoners, the board decides to release Alvarez and Schillinger back into gen pop. Rebadow, still mourning the loss of his grandson, gets transferred to work in the library, where he is thrilled to meet the new librarian, Stella Coffo. Meanwhile, Timmy Kirk, now sentenced to Death Row, pleads to Father Mukada to help exorcize him; Ryan O'Reily seeks to prove his brother Cyril had no premeditated plans of murder; and Winthrop makes Schillinger an offer he can't refuse.

McManus finds he is unable to turn his back on White. Beecher tells the parents of the young girl he killed that he's up for parole. Howell tries to blackmail O'Reily so she can get to Cyril, but he throws her for a loop--and then O'Reily is thrown himself by a family secret.

The infiltration of drugs into Oz has reached unprecedented levels, and the undercover efforts of McManus and Glynn to find out who's smuggling them in backfires in a deadly way. Despite a lockdown in Emerald City, the drugs continue to trickle in—and the blame shifts from prisoners to corrupt officials.

In the "Emerald City" experimental unit of Oswald State Penitentiary, we meet some of the diverse inmates who live within a pecking order of Homeboys, Latinos, Muslims, Irish, Aryans, and Wiseguys. No clear-cut leader emerges—with the possible exception of Kareem Saïd, a Muslim author who preaches non-violence and abstinence. Saïd's arrival doesn't prevent a short-fused Mafia inmate named Dino Ortolani from ticking off just about everybody—a habit that ends up burning him.

Andy Schillinger arrives to Oz and Vern tries to get Warden Glynn to move Andy in with him. McManus is sued for sexual harassment. Sister Pete has questions after a session with Keller. Miguel gets a directive from Hernandez. Said gets old wounds opened when his sister visits. Ryan scores another victory. Officer Hughes makes a "stunning" move on an inmate and Richie Hanlon's death sentence is overturned.