A delivery boy accidentally falls into Krang's new unstable Mutagen and becomes able to transform into anyone he chooses. Shredder tricks him into helping him launch the Mutagen into space and mutate the world, but this "Mutagen Man" has other ideas.

When the city is hit with a sudden termite infestation, the only superhero who can help - Bugman - is too at peace with himself to aid the Turtles in defeating it.