Things haven't been easy for Dr. Grace Thompson. A top ER surgeon at Montecore Hospital, Grace is going through a tough divorce - battling for custody of her daughter, Leah. The stress is high at work as well - dealing with back-stabbing colleagues, and working alongside her ex.
But things are about to get worse.
Grace is drugged during a break-in. She wakes up in a train sleeper car... next to a bloody corpse. A phone on the floor rings: the voice on the other end informs Grace that he has her daughter. If she doesn't kill a stranger on the train, she'll never see Leah again. Trapped on the train and surrounded by strangers, the phone is Grace's only lifeline to her daughter, and the answers she seeks. Who is this madman, and who is the target he wants her to kill? Grace is in a race against time. And the stakes have never been higher...