Once a Ranger, Part I.Lord Zedd and Rita Repulsa's son, Thrax, unites all four Corona Aurora-seeking villain factions into a new Evil Alliance. When they overwhelm the Overdrive Rangers, their connection to the Morphing Grid is severed, and their powers are destroyed. With the gems still needing protecting, Sentinel Knight assembles a team of replacement Rangers, made up of previous (or future) teams of Power Rangers.