A flying saucer from Mars is observing Tubby's town. Tubby is taking violin lessons and makes such a high-pitched squeak that its vibrations cause damage to the saucer and its inhabitants. The saucermen assume that Tubby was doing the sound intentionally as a weapon and decide to capture him. The tiny men from Mars follow Tubby to a sidewalk demonstration of mechanical men, blending in with the toy men. When a policeman runs the salesman off without the toys, Tubby gathers them up, Martians and all, and takes them home. Gloria comes, too. The Martians eventually vaporize Gloria and Tubby and his violin and take them to Mars. On Mars, Tubby and Gloria and the violin are converted back to normal. Unable to duplicate the sound Tubby makes on his violin, the Martians release him to demonstrate. After hearing the sound they flee in terror, leaving Tubby alone to explore. He blunders into the planetary control room and unknowingly steers the planet wildly through space, thinking he is playing a game. The Martians release Gloria to tell Tubby to stop. Tubby aims the planet towards Earth, stopping just as the spire on the tallest skyscraper penetrates the control room. Gloria and Tubby are left clinging to the spire as the Martians retreat back to their proper orbit.; Tubby puts a padlock on the clubhouse door, but finds he doesn't have a key.; Annie is angry with Tubby when he runs his toy car over her doll.; Tubby's mother is afraid he'll break a lamp playing with a model plane indoors, so she sends him outdoors to roller skate. That doesn't solve the problem.