The Lady Vanishes (1938) DVD
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 exists.
However, further enquiries made among the passengers reveal the curious behaviour of a group of foreign government agents who are also travelling as passengers.