Mini Marshals is the twentieth episode of the first season in Team Galaxy. While investigating on a mission, Josh, Yoko, Brett and Fluffy realize that their beloved Earth, along with other planets, is being shrunken down to size.
The episode opens with an alien family settling down for dinner. Before they can start eating, a ray appears from outside the screen and begins shrinking everything gradually down to size. As the shocked family runs together for comfort, they are approached by a large, bellowing shadow.
Meanwhile, at Galaxy High, Mrs. Schragger introduces the class to a new device, the Opticor 8000. As she asks for a student to try out the Opticor 8000, Brett eagerly volunteers, only to be teased by Bobby about his short height. Brett is picked anyway to use it. When using the device, he notices that Planet Zaradon seems to not be located where it should. An announcement from Principal Kirkpatrick appears on screen, with news of a disappearing distress signal from a "friendly planet". He calls on Josh and his team to investigate.
Once in space, Yoko and Josh begin to assess the disappearing planet situation while Brett tries out a new height-enhancement device. Suddenly, they are caught in a drift of space debris, causing one of the hornet's thrusters to stop working. Yoko manages to get the broken thruster working just on time and Brett discovers that the "dust" they are seeing in space at the moment is actually remnants of the disappeared planet, shrunken down to size.
Brett is about to inform Principal Kirkpatrick about the situation when they intercept several distress signals coming from Galaxy High. Immediately, the team decides to turn back to Earth to answer it, but upon reaching Earth, they come across a ship in the process of shrinking their home planet. Several attempts to attack the planet are unsuccessful, and the ship "swallows" the shrunken Earth before leaving. Yoko leaves a tracker on the escaping ship, which the team follows until they reach its whereabouts.
Once on the planet, Yoko, Josh and Brett see a castle and enter it, only to be caught and confronted by the tiny Munchkin Shortstoff as he is playing croquet with the captured planets due to Brett's height-enhancement device. The team is captured and shrunk down to size with Shortstoff's shrink ray.