Murder by Contract (1958)

Claude is a young man with a regular job, no history of trouble with the law and no chance of making any real money. He also has the savvy and emotional detachment to make big bucks as a hit man and that soon becomes his new profession. A string of successful hits gets him sent to Los Angeles for his latest job.

There he is accompanied by two goons: one with a nervous condition and another who worships the young man as a hero. The cold, ruthless hit man finally comes unglued when he finds out that his latest target is a woman. She's a witness, scheduled to testify against Claude's boss, who's guarded day and night by the police. It's her femininity that worries Claude. In his mind, women are unpredictable and don't do what's expected of them. Claude eventually proves that he's the unpredictable one and his own worst enemy.