A rash of apparent suicides takes a sinister turn when a gambling connection is uncovered. Elsewhere, Charlie worries when Alan's retirement disappears, and Larry flounders trying to find his new path.
The team gets a close-up look at the movie business when a producer's desiccated body is found in the desert. Elsewhere, Larry knows that he's leaving but not his destination, and Alan struggles with technology.
The team explores an odd death by some kind of electricity at a decommissioned airbase, finding themselves teamed with an odd character from the Pentagon's Department 44. Elsewhere, David ponders his future and Alan celebrates a birthday.
The team gets into a turf war with a prison warden, and the casualty may be Ian Edgerton and the member of Don's team that he's taken hostage in a desperate attempt to prove himself innocent of murder charges.
When robbers hit a diamond exchange and take hostages, Don and the team find an unlikely ally in convict John Buckley, who may help the team's investigation when they believe the men are copying Buckley's criminal strategies.
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.
Don and the team try their luck at investigating the theft of scratch-off lottery tickets, but the stakes are raised when one of the culprits killed at a botched robbery turns out to be a former lottery winner.
The team searches for a lost shipment of high-caliber firearms when one of the weapons is responsible for random killings throughout the city. Also, Charlie and Amita disagree on a wedding date while Don re-evaluates his relationship with Robin.
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.
Charlie and Amita are getting married at last. While making an arrest, Don's gun is stolen from him and is subsequently used in a series of crimes. Lou Diamond Phillips' character, Agent Ian Edgerton, appears in the series finale.