Six people travel by train overnight from Marseilles to Paris. When the train arrives at its destination, one of the passengers, a girl, is found dead in a sleeping berth. The police led by Inspector Grazzi investigate the other five passengers, suspecting that one of them was responsible. However, as the investigation is stepped up, the other passengers start turning up dead. It is then up to the last remaining two to solve the case, before they become the next victims.
Yves Montand
as L'inspecteur Grazzi
Pierre Mondy
as Le commissaire Tarquin
Jean-Louis Trintignant
as Éric Grandin, étudiant vétérinaire
Jacques Perrin
as Daniel
Catherine Allégret
as Bambi
Simone Signoret
as Eliane Darès, l'actrice éventée (Victime #4)
Claude Mann
as Jean-Loup Gabert, inspecteur stagière de Grazzi
Michel Piccoli
as René Cabourg, l'employé besogneux (Victime #2)
Pascale Roberts
as Georgette Thomas, assassinée (Victime #1)
Charles Denner
as Bob, l'amant sincère de Georgette Thomas
Nadine Alari
as Mme Grazzi
Monique Chaumette
as Mme Rivolani
