The story of the rise of boxer Joe Thomas, which paralleled the life of Joe Louis. Spirit of Youth was originally intended for all-black movie theaters of the time, but proved popular enough to cross over into 'white' theaters, despite a warning from Joseph Breen, the director of the Production Code Administration, that the movie was 'questionable' because it showed a black boxer beating white opponents. The movie's fictional Joe is a poor young man who is devoted to his mother and his childhood sweetheart, Mary (Edna Mae Harris). After success in Golden Gloves competition, he becomes a rising star of the ring but is led astray by vampy nightclub singer Flora (Mae Turner). Dissipated after too much carousing with Flora, Joe loses a crucial fight and is about to go down for the count in a rematch when Mary arrives to offer him last-minute inspiration. Among those offering support are Mantan Moreland and Clarence Muse as, respectively, Joe's best friend and his manager.