Boxer Kid Dynamite is offering $100 to anyone who can stay in the ring with him for three rounds without going down. Uncle Joe is trying to find a fighter who he can train, while keeping the majority of the prize money as a training fee. He thinks he's found that person in Herman Crawley, the strong as an ox but not too bright plumber Kate hires. Joe sets up a makeshift boxing ring at the hotel to train Herman, which doesn't sit too well with Kate. When Joe meets Kid Dynamite and his brazen manager mother Mrs. Hogan, Joe thinks there's no way Herman can lose. So Joe makes a $500 versus the hotel side wager with Mrs. Hogan on the outcome. What Uncle Joe doesn't realize is that Herman has a particular weakness. Uncle Joe has to protect Herman's weakness and find out and exploit the Kid's weakness. Even though Herman prevails, the fight is not as profitable as it should have been.