Shredder tries to pull a rail heist, only for it to go horribly wrong, creating a monstrous new mutant.
Tropes:
- Brutish Bulls: The Mutagen Monster is nothing but hostile, being covered in horns and wanting nothing more than to trample anyone it sees.
- Fusion Dance: The titular Mutagen Monster was created from two bulls mutating into a single bull-beast.
- Too Dumb to Live: The Shredder's only plan when confronting the ill-tempered Mutagen Monster is to yell at it and demand that it obey him.
- Train Job: The Foot Clan attempt one on a pair of trains shipping mutagen-ingredients. Due to Bebop and Rocksteady's typical level of excellence, they wind up causing a trainwreck and drenching a nearby cow-ranch in mutagen, this being the Inciting Incident of the episode.
