When the team foils a robbery of an armored car full of Federal Reserve money and recover bills that trace back to the infamous D.B. Cooper heist, they call on Agent Roger Bloom, who worked on the Cooper case, for help with the investigation. Henry Winkler returns as former FBI Agent Roger Bloom, and Michael Hogan, the uncle of the slain armored car driver and a key player in the investigation.

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.

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.

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.

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..

Charlie meets his mathematical equivalent when lottery agent Jane assists in the investigation into a complex scam that involves thefts of unsold lottery tickets.

The Numbers team tracks a serial killer who targets johns.

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

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.

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.

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.

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, 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.

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...

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 a man is found dead, the team enters the world of alternate reality gaming. However, their investigation leads to a danger for a loved one.

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.

When two FBI agents, part of a unit headed by Don's former mentor, are killed during a shootout with bank robbers, the team must investigate what exactly happened. Also, Charlie and Amita worry when Larry opts not to attend a conference in Geneva.

The team attempts to find the daughter of a geneticist who they suspect was kidnapped by the unstable mother. However, they become concerned about the case when they find evidence that suggests the young girl was a clone. Meanwhile, Charlie and Amita discuss having kids and Liz reveals a dark secret.

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

A shrewd computer hacker cuts the ground from up under an undercover sting operation to bag a cyber crime lord. His actions trigger a turf war putting his life in peril.

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 deaths of two men who were part of a group of friends that had been sexually assaulted by a teacher when they were young boys. Also, Charlie and Amita get a fantastic job opportunity that could put a wrinkle in their wedding plans.

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.

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.