A group of ex-resistance fighters are brought together by Marie-Octobre, the code name of Marie-Helene Dumoulin. The former members of the network have carried on with their lives after the war, but this evening they are going to have to live again a fateful night – the night their leader was killed. He had been betrayed, his name given to the Germans. The search for the traitor puts each personality in the spotlight – and also that of the killed leader, Castille.
Danielle Darrieux
as Marie-Hélène Dumoulin, aka 'Marie-Octobre'
Paul Meurisse
as François Renaud-Picart
Bernard Blier
as Julien Simoneau
Noël Roquevert
as Étienne Vandamme
Lino Ventura
as Carlo Bernardi
Robert Dalban
as Léon Blanchet
Paul Frankeur
as Lucien Marinval
Serge Reggiani
as Antoine Rougier
Jeanne Fusier-Gir
as Victorine
Paul Guers
as Abbot Yves Le Guen
Daniel Ivernel
as Robert Thibaud
Roger Delaporte
as Self - Wrestling Match on TV (uncredited)
