"Matthias Duval is in love, but he can't choose between the two twin sisters Betty and Liz Kerner. To pick up the two sisters, he invents his own twin brother and will play both characters."
Pierre Richard
as Matthias Duval / Mathieu Duval
Camilla More
as Elisabeth 'Betty' Kerner
Carey More
as Elizabeth 'Liz' Kerner
Jean-Pierre Kalfon
as Ernest Volpinex
Andréa Ferréol
as Evie
Jacques Frantz
as Ralph
Jean-Pierre Castaldi
as Charlie
Paul Le Person
as le clochard jazz
Jean-Claude Bouillaud
as l’inspecteur
Henri Labussière
as le maire
Françoise Dorner
as
Isabelle Strawa
Paul Claudon
Gérald Calderon
Alain Huylebroeck
Gladys Berry
Sean O'Neal
Ajzyk Spigelman
Yves Robert
as l’homme dans l'ascenseur
Director
Donald E. Westlake
Novel
Élisabeth Rappeneau
Writer
Boris Bergman
Xavier Gélin
Executive Producer
Vladimir Cosma
Original Music Composer
Robert Fraisse
Director of Photography
Pierre Gillette
Editor
Jacques Saulnier
Production Design
Catherine Leterrier
Costume Design
Thi-Loan Nguyen
Makeup Artist
Daniel Mourgues
Hairstylist
Monique André
Sound Editor
Joël Beldent
Sound Mixer
Jean-Pierre Lelong
Sound Effects
Pierre Lenoir
Sound
Jérôme Lévy
Claude Villand