Serenade to the Executioner (1951)

Original title: Sérénade au bourreau

Schomberg, an enigmatic psychiatrist runs a nursing home. He is forced to close his clinic and disappear to escape the police. But he wants revenge on his wife's lover, Didier Laurent, a former RAF fighter pilot. Didier meets a young trapeze artist, Paula, with whom he falls in love. The happiness of the two young people is disturbed by the assassination of Irene, strangled by Schomberg who casts suspicion on Didier. Fortunately for them Commissioner Ulysses knows the truth and forces Schomberg to commit suicide.