M. Martinet has two daughters Floflo and Lulu, and a passion: boxing. He hires a new boxer named Jim Bougne, who has just arrived from the USA to give lessons to his daughters. He also happens to expect the girls to marry a boxer. When he surprises Lulu with her sweetheart Maurice, who hates boxing, Lulu pretends he is actually Jim Bougne. And when the actual Jim comes along, she locks him up in a closet. Martinet, suspicious, warns Maurice that he will stick with him until the evening when Jim Bougne is supposed to fight with Professor Orino and Marcel Dantesse. Maurice will fight bravely to win the fight and his girl.