Marc Elbichon, a novice private sleuth, is investigating a wave of assassinations bearing a particular characteristic: the perpetrator, dubbed the "telephone killer" always strangles his female victims with a telephone cord.

Didier Bourdon
as Marc Elbichon

Bernard Campan
as Ugo

Pascal Légitimus
as Blacky

Smaïn
as Momo

Seymour Brussel
as Franck

Jean-Claude Brialy
as Le commissaire

Clémentine Célarié
as Annabella

Michel Constantin
as Le directeur du cinéma

Darry Cowl
as L'agent de police

Michel Galabru
as Marraine