While patrolling the streets of the tenderloin district of a large city, plainclothesman Steve Mason enters "Club 46," a waterfront clipjoint owned by Eddie Morgan, a racketeer who poses as the piano player. Annie, a former hostess at "Club 46," is hostess Jo's friend, and when she returns to the club to tell Eddie that he ruined her life, she urges Jo to get Eddie arrested. While at the club, Annie witnesses Jo being harassed by racketeer Red Connolly, and starts a fight. When Dan Walter, a seaman on shore leave, and his two pals arrive at the club, they soon fall prey to Eddie's racket. Although Jo begins to enjoy Dan's company and would rather not "roll" him, she is compelled to follow Eddie's signals to do so. When Jo's attempt to steal from Dan fails, he leaves the place disillusioned. Dan returns, notices that Jo's face is bruised and, realizing that she has been attacked, asks her to marry him and leave with him to live in a small town. Jo accepts Dan's proposal, but when Nellie, who operates a nearby boardinghouse, overhears their plans, she reports Jo to Eddie. Returning to the clipjoint to say goodbye, Jo discovers that Eddie is planning to kill Dan. Jo desperately seeks Annie's help, but the drunken Annie bungles things and allows Dan to fall into Eddie's trap. As a last resort, Jo decides to try to force Dan's departure by ridiculing him before Eddie, and her plan works. When Dan is informed by Annie of the murder plot and Jo's attempt to save him, he returns to the club and starts a fight. While Steve, who has been trailing Eddie in connection with a warehouse hold-up, calls the riot police, Annie grabs Eddie's knife. The police arrive, break up the riot, and Eddie's stabbed body is found on the floor. Annie confesses to Steve that it was she who killed Eddie, and, realizing that the law demands that she be punished for it, is led away willingly as Dan and Jo leave to begin a new life in a small town.