L'assassin connaît la musique.

Lionel Fribourg, a great composer (at least that's what he thinks) has a problem with his noisy environment: he can't complete his unfinished symphony. Of course there is a market for unfinished symphonies but, for all he knows, only one became famous. So he had better find a way to finish it. At long last, he comes across Agnès, a divorced woman who agrees to let him her quiet home. Lionel, full of hope, resumes work...