Up-and-coming racketeer Dutch Schultz joins the Legs Diamond gang in Prohibition-era New York. A bootlegger named Murphy is murdered by Dutch, who falls for the dead man's daughter, Iris.
Iris marries her fiancé, Frank Brennan, a police detective. They need money and Frank accepts payoffs from Dutch, who is forming a gang of his own.
After getting rid of Legs, Mad Dog Coll and others standing in his way, Dutch again makes a play for Iris, but she learns that he killed her father and begins to drink. Frank vows to reform and win her back. Betraying his pal Bo to the mob, Dutch discovers that a hit has been put out on himself as well. While fighting for his life, he is shot by Bo by mistake and is killed.
^PORTRAIT OF A MOBSTER, Monthly Film Bulletin; London Vol. 28, Iss. 324, (January 1, 1961): p. 99.
^McCarty, Clifford (1996). "A Max Steiner Filmography". In D'Arc, James; Gillespie, John N. (eds.). The Max Steiner Collection. Provo, Utah: Special Collections and Manuscripts, Harold B. Lee Library, Brigham Young University.