In New York City during Prohibition, two smalltime hoodlums, Dutch Schultz and Bo Wetzel, join Legs Diamond's gang. While on a project for Diamond, Schultz oversteps his authority and kills a bootlegger, John Murphy, who has an attractive daughter named Iris. Though Schultz leaves Diamond to form his own mob, he is unable to forget Iris, and he persuades her to date him, despite her engagement to Frank Brennan, a young police detective. Upon learning that Schultz is a hoodlum, however, she rejects him and marries Frank. The newlyweds have a rough time of it financially, and before long the weak Frank is on Schultz's payroll of corrupt officials. When Iris learns of her husband's duplicity, she leaves him, becomes Schultz's mistress, and turns to alcohol for solace. After eliminating Legs Diamond and Mad Dog Coll, Schultz beats a criminal conspiracy rap and becomes New York's number one underworld czar. When Iris finally learns that it was Schultz who murdered her father, she moves into a rundown boarding house and becomes a hopeless alcoholic. Frank eventually finds her there, and the two decide to make a new life together. Schultz, meanwhile, is having trouble with the Mafia and he attempts to placate them by agreeing to allow his top lieutenants, including Bo, to be killed. The attack takes place, but, unknown to Schultz, the assassins have orders to kill him, too. Though he escapes, he is shot and killed by Bo, who, mortally wounded himself, mistakes Schultz for one of the assassins.
