Henry Jackson, known as Little Dynamite, is a Golden Gloves champion, who agrees to turn professional when approached by fight manager Ed Watson, despite the opposition raised by his father and Fanny Singleton, his sweetheart. Soon, Jackson is ready to fight for the championship, when he runs into Frank Harrison, an old school friend. Harrison is not the faithful friend that Jackson believes him to be as he is betting heavily that the heavily-favored Jackson will lose the bout. To ensure he does, Harrison introduces Jackson to a hot mama, Jerry Jordan, who is instructed to make him drink, stay out late and generally mess him up by whatever means. The day of the fight, Harrison orders Jerry to slip Jackson a sleeping potion just before he leaves for the fight. Jerry, now in love with Jackson, finally agrees after Harrison threatens her. A few hours before the fight, Jackson, Windy, a Harlem hanger-on, Harrison and Jerry are in Harrison's apartment when Jerry proposes a toast to Jordan. When he is not looking, she slips the sleeping potion into his glass. Windy sees her and switches glasses with Jackson. Jerry, ringside at the fight, sees the boy she loves getting a bad beating.Sobbing wildly, she leaves the arena and runs to a near-by church, where she drops on her knees and prays to God to forgive her and to let Henry win.