Informed by Major Robbie Robertson of slave raids on the planetoid Mimas, Space Patrol Commander-in-Chief Buzz Corry and Cadet Happy go in search of the slavers. Corry and his cadet land on Mimas to speak with the planetoid's governor, Lara. Lara informs the lawmen that the raiders took 50 additional prisoners, including Lara's daughter Dextra. The patrol spaceship comes across the raiders' ship and follows it to Pluto. The raiders release a "space gas", rending Buzz and Hap unconscious.