A shady operator sets up the "Keep Fit Tour" taking overweight folks on a luxury cruise up the Yangtze River, feeding them very little, and providing an exercise regime led by Miss Ching Ching, a true fitness expert. Among the weight-loss hopefuls are a chubby kid who's a TV star, a wealthy Hong Kong woman who's brought a trunk full of snacks, a bossy woman who sneaks her mousy husband aboard in her suitcase, and a factory worker turned political boss. The manager, Mr. Hou, pesters one of the guests, and he finally rebels, taking the guests (and the money) on a protest march into the forest near Nanjing. Will Hou learn his lesson, and will anyone lose weight?