When ex-detective Midge McGowan embarks on a sleeper train to the snowy highlands of Scotland, she is hoping for a relaxing holiday. Instead, she finds herself trapped in a nightmare. The last carriage of the train is rumored to be haunted by a mysterious figure. One of the passengers is a prisoner on release from jail, who refuses to speak to anyone and spends most of his time in his cabin. When a guest is found dead, lying inside a locked carriage with no obvious injuries, Midge has a mystery to solve. She must determine if this is the work of a ghost or if someone has pulled off the perfect murder, all while staying alive long enough to find the truth.