The Murderer Is Not Guilty(1946)

Original title: L'assassin n'est pas coupable

In a film studio, several actors are the victims of attempted murders. Julien Brisseau, a writer, decides to use these facts as the backbone of his new novel. But while he is working on his detective story, young actors are actually killed. Julien thence gets suspected by police inspector Vétillard. To clear his name, Julien undertakes to investigate and find the killer on his own.