A newly built space colony, Terra Venture, begins its journey into outer space to discover a new planet where the human race can thrive. An adventurous youngster named Leo sneaks aboard, and his life will never be the same. On a training mission, Leo and his teammates come across a rift in space, out of which comes a visitor from an alien world.
When this visitor, named Maya, enlists the aid of Leo and his friends, they step into the portal and find a village being overrun by local villain Scorpius' soldiers. In order to battle these evil creatures and protect the planet, the heroes pull Quasar Sabers from a stone, and use their powers to become Power Rangers. Leo's brother Mike falls into a chasm, seemingly lost forever. The planet is frozen in stone by Scorpius' general Furio, and the Rangers flee to Terra Venture, where the stay to protect the colony from invasion.
When the Rangers freed five gigantic beasts from Scorpius, they returned the favor by helping them defeat monsters, first as beasts, and later as Zords, and as the powerful Galaxy Megazord.
A rogue warrior with a mysterious past had appeared on Terra Venture. His name was Magna Defender, and he was on a mission of vengeance against Scorpius, who had killed his son thousands of years ago. He brought with him the magnificent Torozord. It was discovered that Magna Defender had absorbed Mike's spirit to re-energize himself, which was not allowing him to do evil deeds. Magna Defender finally released Mike just before regaining his honor and sacrificing his life to save Terra Venture.
When the Rangers were in trouble, the spirit of Magna Defender appeared to Mike and passed his powers to him, making Mike the new Magna Defender. He had all the weapons and abilities of the original.
Major shake-ups were in store for the crew of the Scorpion Stinger. First, Princess Trakeena abandoned her father, refusing to be metamorphed into an insect. Then, a stranger named Deviot became Scorpius' new general. He unleashed his three powerful Zords on the Rangers - Centaurus, Stratoforce, and Zenith. The Rangers discovered that these Zords were actually the missing Galactabeasts, and they were turned back to the side of good, now serving as the Rangers' newest Zords. This treacherous scoundrel then set up Scorpius' death to take the cocoon meant for Trakeena, but Trakeena returned just in time to prevent it. She returned with great power and fighting ability, and brought along her trainer Villamax, and his sidekick Kegler.
Deviot obtained the Psycho Ranger keycards, and restored them to have them battle the Galaxy Rangers. A distress call from Alpha brought the Space Rangers to help them out. Kendrix and Cassie followed Psycho Pink to an alien planet, where Kendrix was apparently destroyed. Her Quasar Saber was retrieved by Karone, who used it to become the new Pink Ranger.
Deviot's quest for power led him to the Galaxy Book, an artifact retrieved by Leo and Mike on a rescue mission. The power of the book gave Deviot power, but also transported Terra Venture into a lost galaxy, with no way out. This lost galaxy is home to Captain Mutiny, who seeks to enslave the inhabitants of Terra Venture.
The Galaxy book eventually returned the station to normal space. Captain Mutiny followed in his castle, which was destroyed by Trakeena. Deviot managed to escape, and forcibly merged with Trakeena, creating a ruthless new being which attacked Terra Venture, making it crash land on a moon, where Trakeena and the Rangers had a final showdown, resulting in Trakeena's destruction. The inhabitants evacuated to a nearby planet, and the Rangers soon followed. The new planet was revealed to be Mirinoi. The Rangers placed their swords back in the stone, turning Maya's tribe back to normal, and returning Kendrix back to our physical plane.