A bus conductor gets dressed for work in the morning, goes to the toilet, where he is killed by a bomb. The Commissioner and his fat, bumbling assistant, Inspector Charbonnier are put on the case. After interviewing friends, wives, colleagues, and spying on strangers who might be connected, our heroes trace the assassin down to a mental institution where, it seems, the murder victim has been an inmate for the last three years...

Coluche
as L'inspecteur Charbonnier

Jean Rochefort
as Le commissaire Pichard

Roland Dubillard
as Gazul

Danièle Evenou
as Gwendoline

Robert Berri
as René

Jean Luisi
as Barbocelli

Billy Bourbon
as Joseph Ordure

Olga Valéry
as La mère du médecin

Robert Dalban
as L'entraîneur

Virginie Vignon
as Odette Jeandrin