The evil leaders of Planet Spaceball, having foolishly squandered their precious atmosphere, devise a secret plan to take every breath of air away from their peace-loving neighbour, Planet Druidia. They send the evil Dark Helmet to kidnap Princess Vespa on the day of her wedding, in the hope of holding Druidia to ransom. But the princess skips town and joins forces with a mercenary named Lone Starr and his sidekick, Barf.