L'assassin connaît la musique...

Lionel Fribourg, a great composer, has a problem with his noisy environment: he can't complete his unfinished symphony. To find a solution, he meets Agnès, a divorced woman who agrees to let him stay in her quiet home. Lionel resumes work, but an obstacle arises when his daughter-in-law's father, the commissaire de police Fernand Guiot, becomes involved.