Alain Delon made his film debut at the age of 21 in this film, translated as Send a Woman when the Devil Fails, I believe. The strict translation is When a Woman Gets Involved. I suppose either one would do. I had to watch this in French without subtitles as it was all I could find at the time.
Set in Paris, the film is about Henri Godot, (Jean Servais) who owns a nightclub. He hires a young man named Jo (Delon) to kill Boby (Yves Deniaud). Meanwhile, Angele (Edwige Feuillere), Henri's mistress, is hanging around as well.
Then Felix (Bernard Blier) arrives in Paris, meanwhile, with his daughter (Sophie Daumier) by his first wife. He is there to take vengeance for the death of his second wife in a fire that was arson. Jo and the daughter, Colette, fall for one another, which causes some problems. And when the killings begin, a police detective (Pierre Mondy) comes around.
The director, Yves Allégret, enjoyed a successful career, but he was on a downslide by the time this film came along. He unsuccessfully tried to mix noir and comedy. I found this film unimpressive, except for the fact that it is Delon's first appearance on screen.
This film also gave early roles to Bruno Cremer and Sophie Daumier, so there are two generations of film actors. The seniors, particularly Servais and Fuilliere are excellent. Baby-faced Delon in a supporting role starts his 50+ year career as a romantic, cool, but dynamic killer who is still getting his sea legs.
At one point, while enjoying ice cream with Colette, he spots a car that has been following them. He runs out; Colette hears two shots. Jo re-enters, sits down, and continues eating as if he just put a quarter in a parking meter.
The end of the film is ambiguous. I felt ambiguous about the whole movie myself.