Season 2 features a new storyline and cast headed by Suranne Jones. She portrays Laurie Franklin, an off-duty police officer who finds herself caught up in a strange sequence of events beginning when a commuter train is halted by a suicide jumper. Laurie then learns that a newborn baby has been abandoned at the local hospital, and it soon becomes clear to her that the two events must be connected. But both the train's victim and the baby remain unidentified. As she is drawn deeper into the mystery, Laurie realizes this might not be a simple case at all, but something much darker.