Dr. Cordelier, living in a suburb of Paris, withdraws from society to pursue research into the functioning of the human brain. His lifelong friend, Maître Joly, becomes concerned when Cordelier draws up a will that bequeaths his entire estate to a stranger, Monsieur Opale; he cannot understand why Cordelier defends him, considering Opale attacks women and children. After a colleague is killed, Joly confronts Cordelier and discovers the truth behind his friend's behavior.
Jean-Louis Barrault
as Dr. Cordelier / Opale
Teddy Bilis
as Joly
Michel Vitold
as Dr. Lucien Severin
Sylviane Margollé
as Little Girl Attacked by Opale
Jacques Danoville
as Commissioner Lardaut
André Certes
as Inspector Salbris
Jean-Pierre Granval
as Boss of the Short-Time Hotel
Jean Bertho
as First Passer-By during the Aggression
Jacques Ciron
as Second Passer-By during the Aggression
Annick Allières
as Neighbor
Dominique Dangon
as Little Girl's Mother
Jean Topart
as Désiré, Butler
