An alien starship crashes in a swamp in a U.S. National Park. Some mosquitos begin to feed from the alien's corpses, causing them to grow to the size of a vulture. These mutant insects became very agressive, killing every human being they find. Will the few survivors fight successfully against this nightmare...?

"Bags" the boxer (funnyman Tim Conway) and his manager, Shake (Don Knotts), are quite a pair: One is a dim bulb, and the other has a mean streak. Times are tough and they must save their gym, so they line up some moneymaking fights. But when Bags and Shake discover that the bouts have been rigged, they end up with their backs to the wall and must fight back -- literally.