Evil Jim comes across a device that allows him to create complete opposites of anyone. But when he attempts to use it to take on Earthworm Jim and his friends, Peter's transformations may finally come in useful.
Bob the Killer Goldfish invents a device that can transfer "evolution energy" from its target to its user. This devolves the target to a lower life form and takes Bob to a higher stage of evolution. Jim and Peter become its victims.
Jim and Peter find themselves in an alternate world which apparently bears a striking resemblance to The Wizard of Oz. When Jim comes into possession of treasured Sapphire Toe-Socks, they must find a way back to their world before the alternate Queen destroys them.