The SWAT Kats race against time to stop an "undead" evil sorcerer named the Pastmaster, who intends to send Megakat City back into the Dark Ages. But first our heroes must battle their way back from the prehistoric past.

The SWAT Kats must battle the evil Dr. Viper's mutant blob.

While in the middle of a battle against sea monsters who are attacking KatCo oil tankers, the SWAT Kats become caught in of the Pastmaster's time portals, which appears out of nowhere and pulls them back into medieval times. There they find the evil wizard in the midst of laying siege to Megalith City, Megakat City's Dark Ages counterpart, with an army of mythological monsters (dragons, cyclopes, etc.) in an effort to force its ruler, Queen Callista, Callie Briggs' lookalike ancestor, to marry him. And that's not the only romantic complication! When Callista sees Razor pull a certain sword from a certain stone, she falls in love with him, causing T-Bone to become jealous.

An exploration probe returns from its mission in space and is taken to MASA where Dr. Harley Street discovers a yellow viscous substance oozing from inside the probe.

Lenny Ringtail, a crazy comedian, escapes his asylum and finds refuge in a magic shop.

Dr. Viper forms a fiendish alliance with Dark Kat and the Metallikats! The SWAT Kats scramble to expose this slithering, sinister plot. Can they save Megakat City?

Dr. Viper floods Megakat City with Katalyst X-63, an experimental formula that mutates any living thing it touches into grotesque, menacing versions of themselves.

The SWAT Kats are sent through a time portal.

Hard Drive deactivates the Turbokat's weapons.

The Pastmaster brings to life an army of mummy warriors.

The SWAT Kats go underground in order to rescue five miners who have disappeared.

The SWAT Kats must battle the awakened demon, Volcanus.

Dr. Elrod Purvis is mutated into the evil Dr. Viper.