The strange encounter around which Andre Delvaux's film is structured, occurs in 1917, against the background of World War I. As in Delvaux's earlier films, The Man Who Had His Hair Cut Short and Un Soir Un Train, the style is oblique, and there are no simple explanations for the characters' behaviour.
A young pianist from Luxembourg receives a telegram from an old friend, an air force pilot, extending an invitation for him to renew acquaintances at a house in Bray, which is near the Front. En route by train, the pianist reflects upon their relationship, and his collage of memories introduces us to the confusions for which the film seeks no clarification. His arrival at the house offers us some more ambiguous information about his friend's apparent homosexual inclinations and about their mutual relationship with the friend's girlfriend.
On arrival, he finds, in place of his friend, an attractive maidservant. He spends the night with her, but by morning she is gone. He leaves the house for the station, wondering if, in fact, he can be sure of anything that has happened to him.