Set after the events of Power Rangers in Space, four young adults from Angel Grove (Leo, Mike, Kai, and Kendrix) are leaving for the space colony Terra Venture seeking a new world like Earth. They later meet a mechanic named Damon, and on the Moon, a jungle girl named Maya who leads them to five mystical swords known as the Quasar Sabers on her home planet of Mirinoi. After pulling the sabers out of a stone, one of the youths, Mike Corbett, falls into a crevice, but not before passing his saber onto his younger brother Leo Corbett.
With the Quasar Sabers, the teens transform into the Galaxy Power Rangers and use them to battle space villains from two different parts of the galaxy. These villains include Scorpius, Trakeena, Deviot and Captain Mutiny. Along the way, they discover several Zords known as Galactabeasts and make an ally in the form of the mysterious Magna Defender, a galactic warrior. Though he later dies, he manages to reveal that his host body is Mike Corbett and passes the Magna Defender powers to him.
When Deviot revives the evil Psycho Rangers, the Rangers of Power Rangers in Space show up to aid the Galaxy Rangers in destroying them. During this saga, Kendrix Morgan, the Pink Ranger, sacrifices herself to protect the Pink Space Ranger and Terra Venture from Psycho Pink. Karone, sister of the Red Space Ranger Andros and former evil princess Astronema, is given the powers of the Pink Galaxy Ranger from Kendrix (who appears as a spirit), and joins the Rangers in the battle to protect Terra Venture.
Deviot later reads secret words from the Galaxy Book; sending Terra Venture and himself into the “Lost Galaxy”. Here the Rangers encounter Captain Mutiny and his Swabbies. These space traveling pirates live on the back of a massive space faring dragon inside a castle. Deviot reemerges and joins the Captain’s fight against the Rangers and attempts to turn all of the citizens of Terra Venture into his slaves for the purposes of mining for “Booty”.The colony escapes the galaxy after Mike sacrifices his powers to keep a portal open…