Overview: Part 1 of 2. 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.