During the tour of variety stars Nelly & Sky, a guitarist dies, crushed by a spotlight. It was Sky who was targeted, as a second murder attempt quickly proves. To protect the star, Gréco imposes Beretta as guitarist for the next concerts. A big challenge for the inspector, who does not know if he will be able to improvise himself as a musician as his scales are rusty. Meanwhile, Rose discovers, horrified, that the murderer could very well be one of her patients. Indeed, Rico, a very psychologically disturbed musician, is convinced that Sky stole a song from him. Since then, he has sworn revenge.

Two young single women are murdered a few weeks apart. Their common point: they frequented the same marriage agency "For life", in the hope of meeting a soul mate. Annie Gréco decides to trap the murderer by registering with the agency. She accepts dinner invitations from single people who seem suspicious to her. All the service is on the teeth because playing with fire like this, Gréco could well get burned. Rose discovers that Max Beretta is also a regular at the "Pour la vie" agency...