A flying saucer races across the galaxy on its way to the planet Earth. Cosmo Gork and his family are headed for their first vacation on Earth. The Oglook Travel Agency is promising a wonderful time in beautiful, sunny California once the family completes the process of orientation at their underground visitor facility. The Gorks will borrow the identity of a human family, the Wilsons, in order to resemble authentic humans. J.T. Wilson and his family were supposed to be on vacation in Europe but had a last minute change of plan. Instead they, too, will be headed for vacation in California. On the final night of vacation for both families, Cosmo and J.T. accidentally swap families following a tiring day. Cosmo wakes up in the backseat of the Wilson family car on his way to Pipecreek, Texas, while J.T. wakes up on the Vector-12 spacecraft on his way to the planet Growk. Oh, what a mess!