A young man, his girl-friend, and her father investigate racketeers for the District Attorney.
Hank Sherman (Robert Young) gets a job loading produce and is told to pay $10 a month to the protective association. When he refuses, two men beat him up until owner Eli Decker (Samuel S. Hinds) stops them. Decker hires Hank as his chauffeur, and secretary Peg Gattle (Florence Rice) tells him his duties. Hank asks Peg to marry, but she says no. Dr. Simon Gattle (Lewis Stone) gets out of prison after twelve years and is met by his daughter Peg and Hank. Decker asks Gattle to tell District Attorney Paul Scott (Harvey Stephens) about the racketeers. Gattle says that Joe Emerald is the boss and deals in cash. Hank is studying law, and Dutch McTurck (Edward Pauley) offers him a job. Hank warns Decker and offers to help. Hank's brother Steve Sherman (Leslie Fenton) asks Decker to give his boxer a match in the Garden. Decker is killed, and Steve dies in Hank's arms.
Hank asks Dutch for a job, and the association hires him. Hank is sworn in by D. A. Scott as an investigator. While Dutch's "boys" contaminate milk, cops shoot; they flee, and a cop wounds Hank. When Dutch is about to shoot a cop, Hank kills him. Gattle is warned by an ex-con that Emerald is out to get him. Hank goes to Dr. Gattle, who takes out the bullet but warns him not to come back. Hank finds boxer Steamer Krupp (Nat Pendleton) sleeping in his room. Steamer asks Hank to replace Steve as his manager. Steamer wins several fights. Emerald's men offer Hank $10,000 for Steamer and threaten him until he accepts the cash. Hank and Peg see Steamer lose, but Steamer beats up Emerald's men. Steamer tells Joe Emerald (Joseph Calleia) that he fights better for the Shermans. So Emerald hires Hank to be his manager. Emerald wants a champion because he is crippled. Hank asks Emerald to put Peg in a show, and she is sworn in as a D. A. investigator. Peg sits next to Emerald and drinks. While Emerald, Hank, and Steamer talk, she starts a fire. Steamer follows Emerald and saves him in the steam room.
During Steamer's fight the police go to Emerald's steam room to find his vault; but rain cancels the bout. Peg gives her father the key, and he and the police search until they find the vault. Hank finds Peg and signals Scott. Hank and Peg are locked in the vault, and Emerald turns the steam on Gattle; but a policeman blows up Emerald, and Hank and Peg are found kissing in the vault.
In this racketeering melodrama Emerald is portrayed as trying to gain power to compensate for his physical debilitation. The audience roots for the young lovers to overcome the dastardly gangsters.