LAPD's Threat Assessment Unit's Lt. Beth Davis and Det. Jack Larsen search for a stalker with an affinity for fire. Also, Beth meets with an exasperated college student who claims his former roommate is aggressively harassing him.
Beth, Jack and the Threat Assessment Unit (TAU) investigate after a teenaged girl has a stalker break into her house, but quickly realize that she is not the one being targeted. Meanwhile, Perry pays Beth an unsolicited visit at work.
While investigating a series of eerie threats, the TAU team discovers the victim's house has a creepy history and is believed to be haunted. When the danger turns deadly, the team spends Halloween night searching a wild costume party looking for a perpetrator long believed to be dead.
Following a series of alarming attacks on a wealthy philanthropist, the TAU investigates her beleaguered ex-husband and his much younger girlfriend. Meanwhile, Amanda threatens to reveal Jack's dark past.
The Threat Assessment Unit investigates the home of a young actress after she is frightened by an obsessed fan. Meanwhile, Beth receives an unsettling personal letter and Perry gains more access into her life.
The TAU investigates when a psychiatrist is seemingly being stalked by one of his patients. However, they soon find that there is more to the case than meets the eye, while Beth makes a shocking discovery.
The estranged wife of a high-profile athlete is terrorized by a stalker, which may be connected to her tell-all memoir, which is soon to be published. Meanwhile, Janice helps Beth by investigating Perry.
The Mayor of Los Angeles is attacked and the TAU must determine whether he holds a dark secret or has a real stalker. Meanwhile, Janice and Amanda try to assist Beth with her interdepartmental problem.