New York, 1942. The city is mired in crime, the hands of the police are tied, and an avenger nicknamed "Bitter Chocolate" stands up to defend justice. When dealing with gang leaders, he—or she— leaves a bar of bitter chocolate next to the corpses. A private investigator undertakes to find the avenger and hand him over to the one who pays him. He uses the daughter of his colleague Nancy, the police secretary, to get information.