The mice of Cheeseville, who are farmers, are having a Saturday night barn dance. They receive a visit from a little mechanical creature (complete with diapers!) from outer space who looks and sounds harmless (they think he's funny and cute)- until one of their scientists translates the little character's language, and finds out that his father is planning to invade the earth and destroy Cheeseville. When the creature's father comes looking for him, he is 40 feet tall and breathing fire. An urgent call is sent to Mighty Mouse, who flies down and sends the evil aliens back to their own solar system, though even he has his hands full at first.