A rebel army of gophers vows to overtake Mars. Marvin's canine companion discovers the plan during a golf game but can't communicate the information to his master. Without Marvin's help, it's up to K-9 to save the planet on his own.

Space pirates use a disappearo device to render their ship invisible. After they wreak havoc, Dodgers and Cadet must disguise as pirates to claim the disappearo device for Earth before the Martian Commander claims it for Mars.