Rex and Speed of the Space Rangers investigate a strange ship. They discover it is from the distant planet of Dox. Leading the expedition is a Doxian woman named Erda. Her bodyguard is Dav. Dox revolves around the star of Algol. Dox is involved in a defensive war against the Devil Masters of its sister planet, Zod. Rex and Speed assist the Doxians in defeating the Zodian fleet.; Rex Clive investigates the disappearance of the gravity-repelling Plutonian product, Gravitex. Gravitex is formed by manipulating Cosmium ore mined by robots on Pluto. With the aid of his henchman Pojo, Nucleo tries to get away with the theft.; Noxor, intent on becoming the Mighty Monarch of the Saturnian Satellites, is using "Repello Rays" to knock "Moon Hoppers" spaceships out of the sky. Rex, Speed, and Stella defeat the plans, calling the Space Rangers down on Noxor's noggin.; Mighty Voz, is the leader of the half-robot, half-human creatures called the Mechans. The Mechans were forgotten miners of the planet, Kalypo. Van and Loa are captured human slaves. They overcome the mastery of the Mechans when Van devises a slave rebellion with the other human slaves against the Mechans, He manages to cause a flood, putting quit to the Mechans.; Rujon and Dzartz hijack a load of gold leaving the tiny planet Juno, where gravity makes the bars extremely light. Stella Dawn confronts them, but is taken prisoner. They load their ship, a fast space cruiser named the Zodiac. Space Rangers Bob Barry and Jim Jones surprise the crew of the Zodiac, using gold bars to defeat the thieves.; Steve and another prospector are confronted by the landowner when they discover a meteorite filled with diamonds. All three are killed when they shoot it out. Two men arrive at the scene and conclude nobody will bother with the meteor as they walk away. The meteor opens and the real owner of the meteorite peeks his head out. It is a space traveler with wings and a mechanical box on his chest. He says the meteor was his and he had brought it all the way from Jupiter.; Invaders from Galaxy Q-7, based on Pluto, plan to take over the rest of the solar system by invading Mercury, Venus, Earth, and Mars. Spiro reports the plans, and the invaders are roundly defeated.