Ratty is the oldest son in a rat family that consists of a mother (who spends most of her time vacuum cleaning), a father (who is building some strange vehicle in the basement), a grandfather (who most of the time walks around saying "Sure, sure!"), and then Ratty has a whole bunch of siblings. One day Ratty meets Rosetta and falls in love. But how serious is it from Rosetta's part? She, who one day can be ready to leave Ratty after winning a trip, and the next day can ride with the leader of the motorcycle gang to the rat club "Ratz."