Navy veteran Dan Corbett arrives at the New Orleans shipping docks where he's looking for a job. Unknown to him is the fact that shipping docks owner Zero Saxon is a crooked businessman and a racketeer. Using a complex scheme, Saxon is stealing legitimate cargo and switches this cargo for phony cargo. This scheme involves his network of trucks, rail cars and ships. Most longshoremen make extra money by turning a blind eye to the racket and they're also afraid of Saxon's hired killers. Dan Corbett meets nice gal Alma Mae who invites him at the longshoremen picnic where he's introduced to Jack Petty, business agent for the longshoremen's union, and Joe Reilly, Saxon's dock manager. Dan Corbett befriends Joe Reilly, his wife Marie and her brother Scrappy Durant. Joe Reilly is a nice guy and offers Dan Corbett a job on the docks. Unfortunately, Joe is on the take and implicated in Saxon's racket. When he tries to quit the racket and go into a legitimate business, Joe is killed by Saxon's henchmen Deuce and Big Mike. That's when Dan Corbett starts suspecting that Saxon is heading a criminal enterprise. He summons the president of the Longshoremen Association and the Chief of Police to a secret meeting. At the meeting, a plan to expose Saxon's racket and to trap him is agreed upon. However, this plan involves the planting of a radio transmitter into Saxon's cargo crates and Dan Corbett is the only man available for this job. Dan is aware of the danger he's exposing himself to.