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

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.

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.

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.

Don runs into Robin Brooks during an investigation concerning informants and a chess master.

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.

The team sifts through various rumors about a controversial charity organization to find the guilty party after its office building is bombed.

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.

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.

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.

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.