Mutagen Monster

Character voices

 * Leonardo (Cam Clarke)
 * Donatello (Barry Gordon)
 * Michelangelo  (Townsend Coleman)
 * Raphael (Rob Paulsen)
 * Splinter (Peter Renaday)
 * April O'Neil (Renae Jacobs)
 * Irma Langinstein (Jennifer Darling)
 * Vernon Fenwick (Peter Renaday)
 * Shredder (James Avery)
 * Krang (Pat Fraley)
 * Bebop(Barry Gordon)
 * Rocksteady (Cam Clarke)

Errors

 * When the mutant bull was created, two bulls combined, but when it is separated at the end, three bulls are seen.
 * After Donatello and Raphael bring the bull towards a red tarp, Michelangelo is seen with Leonardo's colours.

Synopsis
Shredder and a squad of Foot Soldiers wait next to some train tracks, ready to hijack two approaching trains. Shredder's plan is for Bebop and Rocksteady to switch the trains on the sidings, then steal the chemicals on-board each train, take them back to the Technodrome, and use the chemicals to create a new batch of mutagen. Unfortunately, Bebop and Rocksteady start arguing about who gets to throw the switches in the signal box, and inadvertently switch the trains onto the same track, resulting in a horrific head-on collision between the two trains just outside a ranch. Infuriated, Shredder drags Bebop and Rocksteady back into the Transport Module and returns to the Technodrome.

April and Vernon are assigned to cover the story, and watching the live report on their television, Donatello realises that the chemicals spilling out of the wrecked trains are combining to create an impure form of mutagen, and that there's no telling what could happen to anyone or anything that gets exposed to it. The Turtles race to the scene, and discover that while April is a safe distance away, Vernon has gone to get close-up footage of the crash, putting him in danger of being exposed to the mutagen. Fortunately, Vernon's shoes protect him from the mutagen, and he remains his usual self, but two bulls drink from the pool of mutagen, and instantly fuse into a single, gigantic bull with horn-like protrusions covering its entire body. Seconds later it mutates again, growing even larger and causing its two front legs to fuse into one. The Turtles arrive just in time to protect Vernon from any harm, but are at a loss as to how to deal with a creature with such immense size and strength. Just then, Shredder returns with Bebop and Rocksteady in an attempt to salvage some of the chemicals, but Shredder decides that the mutant bull would be a vastly more valuable prize. Unfortunately, even he doesn't have any idea how to capture it, and after several fruitless attempts by both parties to catch it, the bull splits into two copies of itself. The sight of this is too much for Shredder, and he returns to the Technodrome again. Meanwhile, the two bulls work together to corner April, but crash into each other when they attempt to stamp on April and fuse back into one, bigger than ever mutant bull, which makes off for the city.

The Turtles return to their lair, and after a discussion with Splinter, Donatello realises that because the mutagen was impure, the bull's mutation is not stable, and that by placing it in an atom smasher they could break it down into the original two bulls. Meanwhile, Shredder requests Krang's help in catching the bull, and Krang gives him a giant nose ring and a control device that will bring the bull under his command. However, because Krang (correctly) suspects that Shredder intends to double-cross him, he keeps a more powerful control device for himself. While Donatello sets up the atom smasher at the local university, the other Turtles predictably find that the bull is in a China shop, wrecking the place. Shredder returns to the surface, scaring the bull out of the shop, and the three turtles lure it to the university. However, Shredder follows and has his own lure - a mountain of salt, which the bull stops to lick, and when it does so Rocksteady jumps out of the salt and inserts the control device into the bull's nose. Before Shredder can fully take control of the bull, April's van crashes into the salt truck and sends the control device flying into Bebop's hands. Bebop tries to control the bull himself, but only succeeds in steering it right into the building containing the atom smasher, which Michaelangelo activates, reducing the mutant bull into four ordinary bulls (two copies each of the original two bulls). Shredder returns to the Technodrome cursing his luck once again, and Michaelangelo uses his knowledge of cowboy movies to steer the bulls safely out of the lab.

Vehicles

 * Turtle Van
 * Cheapskates
 * Channel 6 Newsvan
 * Channel 6 Newscycle
 * Technodrome
 * Transport Module