After Charlie and Amita get married and begin preparations for their London adventure, they put a slight hold on their wedded bliss when they assist the team in helping Don track down the whereabouts of his gun after it goes missing.

Feeling guilty over the stabbing, Charlie puts his attention on finding a serial killer using math theories to help the team solve the case before another life is taken.

In the midst of investigating a serious bomb threat, Don and Charlie uncover a secret that could change their lives and the lives of the team forever.

When Amita is abducted, Don and the team’s frantic search for her leads them to the delusional head of a cult, but it is up to a distraught Charlie to discover what the suspect’s bizarre plans for her are.

David tries to get information from one of Crystal's old boyfriends, but he isn't helping. Things get personal for the team when Crystal kidnaps one of them.

Don's life hangs in the balance after he is injured during a raid while investigating a series of home invasions.

The city is in a panic as a sniper goes on a shooting spree and randomly kills several people, including a postal worker. The investigation reveals that more than one shooter is at work. As Charlie works the case, he's frustrated by a sniper expert Don brings in to help out.

The team investigates a decommissioned air base after a woman is found dead there, but their investigation is interrupted by paranormal happenings.

In the season finale, Don and Charlie work together on a case that ends up with them going head to head about their personal beliefs, and one team member will walk away forever.

When an assailant opens fire in the FBI offices, Don and his team must determine his motive and possible connection to a dangerous arms dealer who is on trial. After nearly getting shot, Charlie is shaken and reluctant to return to the offices, which hinders his contribution to the case.

After the events of "The Janus List," Colby escapes from custody. Don and the team go after him, but everything may not be as it seems.

Don learns that counterfeiters are at work producing small-denomination bills, and that they have taken an artist hostage to draw the images for the fake money. If the missing woman isn't located soon, Don fears that she will be killed when her work is finished on the phony cash. The counterfeiters have already murdered at least five people, two of whom stole money from them. The case is made more difficult for Don when his former lover, now a Secret Service agent, is assigned to it.

While consulting with the NTSB at the scene of the wreck, Don learns that this tragedy is one of a series of recreated accidents involving railroad negligence. As is the pattern with the previous train wrecks, an undecipherable numerical code is left at the site, which Don recruits Charlie to solve. By breaking the code, Charlie is able to establish that this accident was a recreation of a deadly wreck that left only one survivor several years ago. Don's investigation leads him and his team to a dangerous standoff with their suspect, who has surprising ties to the railway system.

The Numbers team hunts for a gang of criminals who targeted an unlikely scene of the crime: a televised entertainment awards show.

An FBI investigation into a computer hacking scam that taps into a bank's system to gain access to the identities and financial assets of its customers becomes personal for Don and the Eppes family.

When an ATF agent is found dead under unusual circumstances, Don wants to take the case, which revolves around an elaborate bank robbery, after he learns the victim was his former girlfriend. He then becomes quite introspective as he realizes the impact his career has had on his personal life and decides to turn his attention toward a new woman.

Don has a problem. Crystal Hoyle and her boyfriend Buck are going on a robbery and killing spree. Their terror is spread over seven states, and Charlie is called in to help. However, problems between Alan and Charlie may hinder Charlie's concentration.

Don and Megan are called to the murder scene when the CFO of a powerful energy company - who was about to testify against her fellow executives - is murdered at her home and her son is the only witness. Knowing there could be thousands of disgruntled ex-employees, Don asks Charlie to narrow the list.

When a former mob hit man on death row suddenly has a change of heart and agrees to confess to his crimes, Don has an uneasy feeling about the whole affair.

While tracking down a felon running a heroin ring inside a prison, Agent Ian Edgerton becomes a murder suspect when the informant he meets with ends up dead, sending a desperate Edgerton over the edge when he takes a member of Don's team hostage.

After four people nearly die from poisoning, Don learns someone is tampering with nonprescription drugs. When the perpetrator publishes a manifesto in a local paper, Don is led to believe the person may be a former employee of the drug company that manufactured the drug.

When a DNA synthesizer with the capability of customizing diseases is stolen from the campus where Charlie teaches, Don fears the thieves may be terrorists out to start or advance a bio-warfare program and also believes the theft was an inside job.

Charlie and Don reluctantly enlist the help of imprisoned con man John Buckley to help them catch a crook who's using Buckley's M.O. to rob the Diamond Exchange..

Don and his team must race to save the hostages being held on a hijacked bus.

Don talks to his therapist again, and while he's gone, the team races to find an eleven year-old boy being held on a $3 million ransom, and time is running out...

Various people in the L.A. area with seemingly nothing in common start to become extremely sick and die on the same day. Don fears bioterrorists may have released a deadly virus into the environment. While he tries to discover whether anyone is behind the outbreak, Charlie tries to locate the point of origin.

The FBI becomes involved when the bodies of young Asian girls are washed up on the beach. The situation becomes more critical when it is discovered one girl has avian flu. As the investigation continues, Don and his team discover a connection between the girls and the sex trade industry. Meanwhile, Amita considers a transfer to Harvard University, which causes Charlie to re-evaluate his feelings for her.

A dangerous felon escapes when a prison bus crashes and the FBI has reason to fear he's intent on revenge against the witness whose testimony put him in jail. However, finding the elusive killer proves to be a complicated challenge. Don teams up with Agent Billy Cooper, his former partner from the FBI's Fugitive Recovery Division, and Alan worries that Don's going to return to a more dark and obsessive time in his career.

To help capture a serial rapist-turned-killer, FBI Special Agent Don Eppes recruits his genius brother Charlie, who uses a mathematical equation to identify the killer's point of origin by working back from the crime scene locations.

When Don and his team are called to the scene of the murder of a Los Angeles gang member, they learn they are investigating the murder of another agent who had been working undercover.

$50 million dollars in medical relief is up for grabs after the shipment is stolen. But there's a catch--someone other than the FBI wants to recover the shipment. Don and the team find themselves pitted against blackmarketeers in a deadly race for the supplies.

Don and his team are called in when a woman attempting to rob a jewelry store in Beverly Hills is shot by a security guard. Charlie assists the FBI by using the keyless remote from the woman's car to help identify her and locate the store owner's kidnapped wife and daughter.

A truck carrying radioactive material is stolen, and the thieves threaten to set off a dirty bomb in L.A. in 12 hours if they aren't paid $20 million. While Don attempts to track down the truck, Charlie tries to come up with the most likely location where the bomb may be detonated to inflict the most damage to the population.

A man wanted for stock fraud is found garroted in his apartment, and the crime is eerily similar to a murder committed a year earlier, a case in which Don closed when an ex-con confessed. Now, Don must re-investigate the old case to determine if he put an innocent man in jail. He asks Charlie to go over the evidence to see if he missed anything the first time around.

When a passenger train collides with a freight train David (Alimi Ballard), Don, and Colby are called in to help rescue survivors and to investigate the cause of the crash

The team gets a last minute tip that could exonerate a dangerous mob boss who is about to be executed; Charlie tries to help the CalSci basketball team break their losing streak.

Don, Charlie, and the team search for a polygamist who is on the run. The man is on the FBI's Ten Most Wanted List for rape and murder.

Charlie's life is put in danger when Don brings him in on the case of a missing reporter.

When a wealthy heiress is kidnapped, Don and the team race against the clock in hopes to find her. However, the motivations behind her disappearance aren't what they seem.

Don feels responsible for a life lost. The victim was in the Witness Protection Program, but she wasn't the only one keeping secrets...what is Don hiding?

An actor on his way to stardom finds himself in the middle of a murder investigation when a young woman is murdered in his house.

When a car crashes into a busy coffee shop, the team discovers the fatal act might not have been an accident.

The team searches for a pair of limited edition sneakers after they are stolen from a foreign ambassador.

A feud between Chinese gangs leads to the kidnapping of an undercover agent and the reappearance of Samuel Kraft.

Don, Charlie, and the team attempt to stop a serial killer who is seemingly obsessed with people resembling Biblical figures.

Don turns to his newly found religious beliefs when he is forced to deal with an escaped criminal who is bent on seeking revenge.

When two police officers are killed while eating dinner out, Charlie tries to figure out where the killers will strike next. Don's superiors make him see the department shrink.

Don and the team reopen a cold case when a LAPD badge turns up at a construction site. When Charlie joins the investigation, they attempt to track down the owner of the badge, an officer who has been missing 17 years. Meanwhile, Alan is informed that he's being sued.

Don and the team investigate when a magician mysteriously vanishes during an illusion.

Charlie is forced to turn to his arch rival for help when a vigilante group goes after a career criminal.

The problem of the disposal of toxic waste becomes real to Don, Charlie and the team when several children are injured after a sinkhole collapses underneath a school playground. Charlie attempts to help with the case, but faces opposition from his new boss.

Don and his agents are asked to investigate when a search team finds three dead women in the wilderness who were apparently murdered under bizarre circumstances. The case becomes more suspicious when Don learns the search team was led to the crime scene by a psychic. When the psychic offers to help the FBI in solving the crime, Charlie is determined to prove the psychic is a fraud.

Don and the team must investigate a religious cult after scores of followers are poisoned.

After an extremely expensive yacht sinks in the middle of a race, Charlie is put between a rock and a hard place when Don and the NSA need his help on the case.

One of David's closest friends is called into question after a man dies while boxing with him. When it turns out this is not the first time such an event has happened, things look even worse. Charlie is busy practicing what little he knows about poker, so he can take Larry's spot in a tournament.

Don and the team bust a meth lab, but when Don has a feeling there's more to the organization than just what's on the surface, his intuition is put to the test.

Don, Charlie, and the team take on unknown terrorists who may be using nerve gas to undermine Los Angeles' water supply.

Don and the team attempt to figure out what happened when a Chinese interpreter turns up dead.

The FBI becomes involved in the stalking of a popular singer after she is threatened by an intruder in her house and reveals a series of threatening letters she's received through the mail. Charlie determines the letters are from two different people after analyzing the handwriting. When a photographer is found dead near the singer's house, Don believes the photographer was murdered and his death is somehow related to the stalking case.

When a researcher who specializes in Native American antiquities is killed at the museum where she works, the FBI is called in because the museum is on federal land.

When a musician is murdered, Don and his team must race to find the culprits. They need Charlie's help, but he is busy with Amita's parents coming for a visit.

When eight people, including two police officers, are gunned down in a coffee shop, Don and his team uncover a trail of blackmail, corruption and romance; McGowan expands his investigation of Charlie and Don.

Robberies the storybook hero would have been proud to claim plague Don and Charlie as they attempt to catch a do-good thief who is donating his spoils to charity.

Two rock climbers in possession of a large stolen diamond are killed, and Don and the team hunt for the murderers; Charlie considers whether he should have his FBI clearance reinstated.

Don and the team are left with little recourse when a former FBI subcontractor takes a team member hostage.

The gang uses their math--and a reluctant gun merchant named Randall P. -- to track down a missing shipment of new, deadly but defective assault weapons which are hidden among the thousands of containers in one of L.A.'s busiest ports.

The team investigates the theft of a graphic comic book.

Don and his team are called in to investigate who is behind a deadly gambling ring that is running a high-stakes Russian roulette tournament. Also, Don and Charlie become concerned about Alan's financial health.

Don and his team hunt for an ex-Marine wanted for murder. Things become confusing, however, when the Marine's family is kidnapped. Is there more to this case than meets the eye?

When a case against a weapons smuggler falls apart, the team takes a closer look at the jury that heard the case, searching for signs of jury tampering.