When the demon Triskull teams up with Trakeena, who somehow survived the end of last season, it will take the combined might of the Lightspeed and Lost Galaxy Power Rangers to stop them!
Deviot returns to Trakeena, forcing them both into the cocoon. Now combined as one, the new Trakeena orders an all out attack on an already damaged Terra Venture as it nears a new planet on which to settle.
After losing their first battle against Titanisaur, the Power Rangers must rally together when it returns. Then, Mike volunteers to go undercover and try to help Captain Mutiny's slaves, while Kai and Leo use the Galaxy Book to find a way out of the Lost Galaxy.
Thanks to new villain, Hexuba, the Rangers find that the actions in their dreams are also happening in real life. Then, in an attempt to wear out the Rangers, Hexuba sends previously defeated monsters to attack them.
Captain Mutiny's pet, Grunchor, is let loose on Terra Venture, and not even the combined might of all of the Zords can stop it. Then, Leo and Damon are captured while trying to spy on Mutiny. As they are left to bake and dehydrate, they maintain sanity by recalling most of the events of the season so far.
Deviot manages to use the Galaxy Book to attain greater power, but in doing so, he sends Terra Venture into the Lost Galaxy. Then, Captain Mutiny welcomes the space colony to the Lost Galaxy, but all is not what it seems.
When Magnatox steals Leo's powers, Karone has a way to help Leo restore them. But, it involves facing up to an evil act she once committed as Astronema. Then, Damon comes up with a new device in his bid to become Chief Mechanic, but someone else steals the plans and takes credit for them.
After managing to break free of Deviot's control, Psycho Pink looks to retrieve the Savage Sword, leaving Kendrix and Cassie to stop her. But when the entire universe is threatened, one of them will have to make the ultimate sacrifice. Then, it's the Rangers vs. Trakeena to recover the lost Quasar Saber, but the Rangers receive help from an unexpected source.
While Villamax and Keglar build a laser cannon, the Rangers have to deal with Chameliac, who can copy all their moves and powers. Then, Deviot restores the Psycho Rangers, so the Galaxy Rangers team up with the Space Rangers to stop them once and for all!
Loyax is an old, battle-hardened warrior who used to be good, but has been corrupted by evil. When he's sent for a final battle against the Rangers, can Maya help him return to the good guys? Then, when Leo's new girlfriend is captured by a monster, he has to deal with her overprotective brother, who is determined to save her himself.