When the Powerpuff Girls try to stop Mojo from doing a crime an animal activist group comes to his rescue protesting that the Powerpuff Girls can't harm him because he's an endangered animal.

There's a new Powerpuff Girl in town...or so she would have you think! Her fiendishly foul plot: to trick Santa into turning her into the fourth Powerpuff Girl! (And, in the process, make him believe the Powerpuffs have been very, very naughty!) Now, Bubbles, Blossom, and Buttercup must explode into a Yuletide tornado of bad-girl-thwarting action to put Princess in her place—and keep Christmas from disappearing forever!