Intrigue, espionage and the effects on the lives and futures of passengers aboard a Trans-Continental Express emerge when a girl traveller returning from a holiday strikes up an acquaintance with a middle-aged English governess.

During the journey she mysteriously disappears from her compartment. The girl, seeking an explanation for the disappearance, is accused of hallucinating and is nearly convinced that her new friend does not exist. However, further enquiries made among the passengers reveal the curious behaviour of a group of foreign government agents who are also travelling as passengers.

Hitchcock was actually second choice as director. The production was ready to roll as Lost Lady, directed by Roy William Neill, with Charters and Caldicott already in place, when Neill became unavailable and Hitchcock stepped in. (117 pictures)