Unknown to his clients, publicity man Al Bolger handles the accounts for both Madame Gloria and J. Hamilton Gibbs, who run rival body building institutes. When Gibbs sets out to select the annual Gibbs Physical Culture Girl, his physical training director and none-too-good professional boxer, Jimmy Conley, tips off his fianc?(C)e, Pat Hilton. Gibbs learns that she is the secretary of Madame Gloria, and awards her first prize as an example of the benefits of his club. Jimmy has promised Pat to give up the ring after his next fight, which unknown to him is fixed in his favor, and when his opponent claims he was hexed, sports writers dub him Kid Hex. Madame Gloria, to demonstrate her 'mind over matter' theory of body building by breaking up the romance of Jimmy and Pat is aided by Gibbs' niece Helen Gibbs who decides to move in on Jimmy for herself, and Bolger arranges to have Pat walk in on an innocent meeting of Jimmy and Helen. Jimmy then signs to continue to fight as Kid Hex, not realizing that all of his bouts are fixed in advance. Pat learns this and tells him his next fight with Killer Kane has been rigged for Kane to take a dive in the fourth but Jimmy does not believe her. She tells him to pretend to be hurt in that round and see if Kane carries him along. Pat then promises Rocco, Kane's manager, $2500 if Kane loses the fight. Rocco takes the money but instructs Kane to lose as planned anyway. Jimmy fakes an injury and realizes Kane is carrying him as Pat said he would and, in a clinch, demands that Kane fight or he will report him to the fight commissioner. Kane knocks out Jimmy in short order. Jimmy, realizing he isn't a great fighter, retires and resumes his romance with Pat and takes a job as health director of a boy's club.