The Pastmaster wants to bring back the Dark Ages and heads to the Megakat City Museum of History to search for his spell book, the Tome of Time. Callie is at the museum preparing for the opening and calls the SWAT Kats for help.
Dark Kat, the Swat Kats mysterious arch-nemesis, plunders a nuclear power plant in order to build a doomsday bomb to blow up Megakat City and create his own Darkkat City. We also see the Swat Kats origin story.
The 300-story Megakat Tower office is taken by Dr. Viper, who seizes the structure with his army of monstrous, acid-spitting "plantimals." T-Bone runs interference in the Turbokat while Razor sneaks in the building and tries to stop Viper.