The serial killer resurfaces after 20 years of silence and contacts the Behavioral Analysis Unit with the promise that he will kill another victim in the next five days. As the team springs into action, Gideon enlists the help of a former colleague who worked the case when it was fresh to help find the killer.
Lightman's team investigates potential sabotage at a pharmaceutical company owned by a longtime friend.
The squad frantically searches for a missing child, and is devastated when the case becomes a homicide. Irvin learns he's coming into a large inheritance. Sipowicz is teased over his relationship with McDowell.