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.

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.