In the Season 3 premiere, it's months after Peter's death and Megan returns to work, only to learn she's been teamed with a detective with whom she has a past history. She, Det. Sullivan and his rookie partner are up against a serial killer who targets young war veterans. The stakes become higher after she gets a call from the killer and is told he's holding her teenage daughter, Lacey, hostage.

A murder being investigated by Megan and Tommy appears to be the result of child abuse, but the victim's parents claim their daughter was possessed and the devil killed her, and that he is now zeroing in on their other daughter.