[1] The screenplay concerns a writer who narrates a crime story for a fellow passenger on a train journey.

[2] A middle-aged woman, Miss Owens, recognises her fellow train passenger, mystery writer Larry Gordon, from a photograph on the cover of one of his books she is reading.

Two female stowaways, actresses out of work and short of money, are found hiding in the guard's van.

Taking shelter in the station waiting room, the lighting fails and in the darkness officer Peterson is shot and killed, enabling Harding to be released by accomplices and they attempt to make an escape through the snowy darkness, but conditions force them to return.

Knowing that the train had been cancelled, other police arrive to provide support to officer Peterson, and the involvement of the other passengers is revealed.