When the junk men come by, they mistakenly empty Martin and Tim's garage instead of Mrs. Brown's, and in doing so take Martin's space ship. Mrs. Brown has no idea the name of the junk yard, but there was a witness to the incident: Booboo, a neighborhood dog. Booboo, with the help of his dog friends and acquaintances, helps Martin track down the junk yard. When Martin and Tim get to the junk yard, they find out that the ship has already been sold to a Mr. Carter, who is using it as a "rocket" carousel at a children's amusement park. Mr. Carter refuses to sell it back to Martin. So Martin decides to disappear and fly the spaceship away, although he does slip Carter the money for the ship anonymously. Martin has one other debt to pay: a steak dinner for Booboo and all his friends for all their help.
