Tells the origins of Leatherhead, who started life as an exotic pet which ended up in the sewers after being flushed down a toilet. He was found by two Utrom scientists and taken back to their lab at the TCRI facility for study. While there he was accidentally exposed to a mutagen and grew larger and more intelligent. Years later, after fighting with Samurai Jack and the Ninja Turtles, Leatherhead has returned to roaming in the sewers, where he is now being hunted down by Agent Bishop, a prejudiced agent who wants to push the extinction of mutants.
