When ex-detective Midge McGowan embarks on a sleeper train to Scotland, she's hoping for a nice relaxing trip to enjoy the snowy highlands.

Instead, the journey quickly turns into a nightmare. The train has a haunted history, as multiple witnesses have claimed to see a shadowy figure jumping out of the last carriage, before reappearing on board and repeating the loop.. One of the passengers is a mysterious prisoner on release from jail, who won't speak to anyone and remains locked in his cabin, with a guard posted on the door.

And then the lights go out, the train stops, and someone turns up dead. Their body is found inside a locked carriage – with no way in or out – so how was the crime committed? Is this really the work of a ghost? Or has one of the guests just pulled off the perfect murder? The only thing Midge knows for sure is that not all of them will reach their destination alive...