Peter MacNicol returns as a regular cast member. Colby is being interrogated by a man named Agent Kirkland, who passes him a handcuff key and gives him escape instructions. Don and his team get information about and from Colby and must figure out if that information is reliable then realizes that everything about Colby being a double agent may not be what it seems.

The death of a Hollywood wannabe leads to a famous actor, his friends, and a possible double. At the office, David has difficulty dealing with Colby's return.

A car crash into a building has ties to street racing and possibly a cold case.

Charlie is uncomfortable when the team has to use a numerologist to solve the current case, that has religious overtones.

The perfect bank heist almost stumps the team when the profits are donated or returned to their rightful owners, and Don struggles with management issues.

Don is devastated when he thinks he led a killer to a secured witness, and Charlie sets out to prove he wasn't responsible.

Amita's life is put in danger when she consults on a case involving an on-line role-playing game.

A wealthy man's daughter is kidnapped, and Megan is astounded by his behavior while the team tries to rescue her.

In this episode, it is discovered that someone has stolen, recreated and sold several copies of an extremely rare comic book. Christopher Lloyd plays the original creator of the comic book, who no longer benefits from his past creations. Having thought that his comics wouldn't be worth much in the future, he either lost or sold his entire collection and regrets it now that he and his wife live on very little. His young friend and fellow comics artist, played by Ben Feldman, publicly humiliates the rich man who owned the original before it was stolen.

David is held hostage in an elevator at the F.B.I. building, and Don keeps brushing aside Charlie's suggestion to save David as an all-out assault is planned.

Charlie's life is put in danger after he gives an interview about the case he and Don are working on together, attracting the attention of the kidnappers of an investigative reporter.

Don's team tracks a serial rapist who uses his position as a cop to entrap his victims.

A meth lab bust yields a surprise arrest that stymies the team when they can't figure out why he was in the area, and Megan disagrees with what Don chooses to do to get his answers.

A.U.S.A. Robin Brooks is back in town, and her involvement in Don's case brings back memories as they try to keep witnesses alive. Meanwhile, David attempts to bond with a young man who's in the chief suspect's thrall.

Clay Porter returns to the U.S. when his father and sister are taken hostage, and Don embarks on a deadly cat-and-mouse game to try to catch Porter and rescue his family.

Larry finds himself fighting his own bigotry when he assists Don and Charlie's investigation into the poisoning of cult members.

The murder of a rapper puts Charlie to work analyzing the mathematics of the music business in the same week that Amita's parents come to town, and Megan has asked for a week off without discussing it with Don.

When one of Charlie's friends, a scientist at the university, is arrested for terrorist activities, it puts him at philosophical odds with Don. And as he works to prove the man's innocence, his beliefs may jeopardize his career.