Old Tom is getting in Angela's way as she tries to tidy the house, so she suggests he goes outside and find a friend. However, outside Old Tom is teased by Billy and, worse, trapped by a savage dog. He is saved at the last moment by a young girl called Lucy. They hit it off immediately, and Lucy invites Old Tom around to her place to play. Unfortunately, they are followed by the savage dog, who bursts into Lucy's house and causes mayhem. Old Tom and Lucy lock the dog in her room and escape, just as her parents come home. They think Old Tom caused all the mess and forbid Lucy from seeing him again - that is, until they accidentally let the dog out. Then Old Tom and Lucy, using one of Angela's vacuum cleaners, manage to get rid of the dog, and teach Billy a lesson.

Angela goes shopping for a playhouse for Old Tom and ends up buying an old rocket ship. Old Tom loves it and, with his best friend Lucy, they decide to fly it to Mars. Angela thinks they are just playing (after all, the booster rockets have been taken off) and she goes along with their little 'fantasy'. However, while she is cleaning the rocket, it takes off - Old Tom had used one of Angela's vacuum cleaners as the propulsion. The rocket flies off into space with Old Tom on the inside, and Angela on the outside, battling meteors and satellites. Finally, Old Tom lets her in, just as the rocket careens out of control and crash lands on an unknown planet. Angela is sure they're on Mars - but one of the aliens looks familiar. It's Lavinia, and they have literally 'crashed' her garden party.