Wall Street broker Robert Cain, Sr., is jailed for embezzling. His college graduate son Bob then turns to crime to raise money for his father's release. As assistant to mobster Mickey Dwyer, then falls for Dwyer's girl Lucky. He winds up in the same prison as his father.

University professor George Kingsley is struck by gangsters while crossing the street, leaving him with brain damage and one of the gangsters, Cannon, paralyzed. Kingsley's friend Dr. Sovac attends to both men, and when Cannon offers him a reward for aiding his recovery, Kovac transplants part of Cannon's brain into the dying Kingsley's skull, creating a dual personality.

Naive and idealistic Jefferson Smith, leader of the Boy Rangers, is appointed to the United States Senate by the puppet governor of his state. He soon discovers, upon going to Washington, many shortcomings of the political process as his earnest goal of a national boys' camp leads to a conflict with the state political boss.

In the underworld of Manhattan, a woman dares to stand up to one of the city's most powerful gangsters.