309: Waste Not
As the FBI tries to prove that a corrupt construction company is to blame because they have been burying containers of toxic waste under school playgrounds, they discover that the students in the school have a higher rate of cancer and neurological problems. Charlie tries to mathematically prove cause and effect between the pavement materials and the cancer clusters. Meanwhile, Millie, Charlie's new boss at Cal Sci, orders him to spend less time helping out the FBI and more time in their department.
Though the program was discontinued, Don and the FBI learn that someone is still able to make the conditioning work on former subjects and is using them to commit murder. Meanwhile, Larry announces he is taking a leave of absence from the university to travel on the next space station crew rotation.
311: Killer Chat
312: Nine Wives
When a teenage girl is found almost beaten to death, Don and his team discover that she escaped from a polygamous cult headed by a fundamentalist leader who is on the run from the FBI. They discover that the girl's mother, who is also a religious zealot, "gave" her daughter to the leader. Meanwhile, Charlie and Amita try to decipher a chart that was found at the leader's last known location, hoping it will lead them to him. Teri Polo ("Meet the Parents") guest stars as Rachel Willons, an agent from the California Bureau of Investigation who has been tracking the cult leader for over a decade.
313: Finder Keepers
The FBI asks Charlie to retrace the path of a marine salvage barge because Don suspects a murder took place on board. However, Charlie is put in a difficult situation when the National Security Agency (NSA) also requests his help to find the yacht for the confidential case they are working on. Meanwhile, Liz and Don try to figure out a way to make their personal relationship work after she is permanently transferred to LA. Kathy Najimy ("Veronica's Closet") returns as Dr. Millie Finch and Aya Sumika ("The O.C.") returns as special agent Liz Warner.
314: Take Out
During the investigation, the FBI discovers that the thieves steal the restaurant customer's credit cards so that they can run up charges at a fake Internet store and then route the money to offshore accounts. Charlie tries to pinpoint where the money is being laundered to prevent more restaurants from being hit. Meanwhile, in the wake of the Crystal Hoyle shooting, the FBI forces Don to talk to William Bradford, an occupational psychologist and FBI consultant whose specialty is trauma recovery.
315: End Of Watch
The police investigating the case believe that a former gang member-turned- activist was responsible for the police officer’s death because he was seeking revenge for the murder of his brother. However, Charlie analyzes the data on the case and discovers the location of where the victim was killed, leading the FBI to a tangled web of suspects, informants and dirty cops. Meanwhile, Don and Liz take their relationship to the next level.
David's friend, Ben, becomes the main suspect after the FBI learns that the victim was poisoned, and another fighter who sparred with him also died in the ring while training. David and the FBI try to find evidence to clear Ben even though they believe that he might be knocking off the competition to improve his ranking in the league. Meanwhile, Charlie tries to fulfill a promise made to Larry to enter Cal Sci's poker tournament to defend Larry's title against his longtime poker nemesis. Tito Ortiz, a former light-heavy-weight Ultimate Champion Fighter, guest stars as Tino Alva, the defending champion in the all-Out Fighting League.
317: One Hour
In Don's absence, Megan takes charge and suggests that the team search through the mogul's sordid past and long list of enemies. Later, while the suspect leads the FBI on a maze through the city of Los Angeles, Charlie races against the clock to find the piece of the puzzle that will help find the kidnapper before time runs out. Meanwhile, during his meeting with his psychiatrist, Don is surprised to discover that he has control issues.
319: Pandora's Box
320: Burn Rate
321: The Art Of Reckoning
322: Under Pressure
323: Money For Nothing
324: The Janus List
401: Trust Metric
Agent Colby Granger lands in prison after the discovery that he was a mole within the FBI, but he escapes, and it’s up to Don and his team to track him down and uncover the truth. Val Kilmer ("Déjà Vu," "Top Gun" and "True Romance,") Guest Stars As Mason Lancer, The Mastermind Behind Events That Exposed Colby as a Mole.