Paul Dorgères, a wealthy industrialist, has been mysteriously murdered. The investigation is entrusted to the experienced Chief Inspector Bonnardel and his young rookie assistant, Inspector Richard. Suspicion turns to his mistress Catherine Villard, with whom he had just broken up on the night of the crime. She is soon arrested and charged. However, Inspector Richard discovers a button at the scene of the crime which could help him to trace the trail and confound the culprit(s).
Yves Deniaud
as L'inspecteur-chef Bonnardel
Yves Vincent
as L'inspecteur Richard, jeune assistant débutant de Bonnardel
Élina Labourdette
as Catherine Villard, maîtresse de Dorgères
Henri Crémieux
as M. Phalempeau, homme d'affaires
Robert Dalban
as L'inspecteur Sylvestre, adjoint de Bonnardel
Jean Debucourt
as Maître Landry, avocat pénaliste, ténor du barreau
Marie Déa
as Mme Le Mesles
Marcel André
as Le médecin légiste
Marthe Mercadier
as La détenue-manucure
Charles Dechamps
as Le juge d'instruction Ferrand
Henri Nassiet
as Paul Dorgères, homme d’affaires
María Riquelme
as Étiennette, la concierge
