Henri Corseaux

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.

After witnessing and accidentally helping several thugs get away with a heist, the women rooming together notice through their telescope that the stolen loot is in the apartment right across the street. They plan their own burglary of the already stolen loot.