The son of Lord Zedd and Rita Repulsa, Thrax, unites all four Corona Aurora-seeking factions of villains into a new Evil Alliance. When they manage to overwhelm the Overdrive Rangers, their connection to the Morphing Grid is severed, and their powers destroyed! With the gems still needing protection, Sentinel Knight assembles a team of replacement Rangers, made up of members of previous (or future) teams of Power Rangers. No longer having Ranger powers, the "former" Overdrive Rangers return to their civilian lives. All but Mack, who learns of Thrax's plans to destroy Sentinel Knight, and seeks out the only item capable of doing so, the legendary sword Excelsior. Will he be doing this alone, or can the call of action prove the adage of "Once a Ranger, Always a Ranger" to his former teammates? Meanwhile, their replacements, the team of Retro Rangers, head to Angel Grove to seek out the only being capable of repairing the Morphing Grid: Alpha 6! Even if they succeed, can two combined teams of Power Rangers stop Thrax for good, and permanently break up the Evil Alliance?
