The New Mutation is a the fourth episode of season 9 of the 1987-1996 series. It originally aired at CBS on 7 October 1995.
The Turtles track the TechnoGang to Hyper Dyne Labs, where a highly volatile fuel called X-Fire is produced. But as they try to keep Carter from running amuck, the military police come in and reveal something shocking: the TechnoGang is authorized to take the X-Fire to Dregg's base, and the Turtles are seen as trespassers. They barely manage to escape.
A debate breaks out in the lair about whether they should use more high-tech weapons: Raphael and Michelangelo think they should use blasters and the like, while Leonardo is against it. Splinter argues that they should be more focused on exposing Dregg's evil.
April alerts the Turtles that Dregg has been given access to Bio-Tech labs. They alert the media and infiltrate Dregg's base, finding strange creatures growing inside tanks. One of the tanks is ruptured, and an alien slug creature - later referred to a Slor - hatches and slithers out of the building.
As they're cornered, the Turtles' second-stage mutations are triggered, which the media takes as proof of them being evil like Dregg has said. But fortunately they also are nearly invincible to energy blasts, allowing them to escape to a nearby playground. Raphael berates Leonardo for his failed plan, and they decide to head to Killdeer Mountain to do some damage to Dregg at his main base of operations.
Dregg is in the process of creating an impenetrable citadel, from which he plans to use the X-Fire to fuel a laser cannon that will destroy the cities of the world. He sees the Turtles approaching, but is confident that they will never escape alive. When cornered by laser fire, the Turtles hyper-mutate once again and break their way into the citadel. Leonardo is reluctant to use brute force to defeat Dregg rather than their wits, but Raphael is unimpressed by that argument.
April contacts Carter with news of a giant slug creature. Carter finds it terrorizing people, eating statues with acidic spit, and smashing through buildings. He decides to use the wrist-mounted weapon that he and Donatello had been working on, which only annoys it.
As they head towards Dregg, he sends a robotic attacker called the Arachnicon towards them. Just then their mutations fluctuate again, returning them to normal. The robot easily knocks Donatello and Leonardo through the floor, where they spot the X-Fire being loaded into a laser gun. Leonardo has the idea to throw all of the fuel into the generator, where it would destroy the entire citadel. But the plan is complicated when they mutate again, increasing the chances of setting it off.
Raphael and Michelangelo are still being chased by the Arachnicon when they hyper mutate once again, which allows them to destroy the robot... only for it to regenerate as two, and then four. Each destroyed robot comes back as two new ones. As they turn back to normal, Michelangelo realizes that they need to use their wits, and manages to trick the robots into attacking the floor and falling through.
Carter alerts them to the mayhem that the Slor is causing, and Donatello deduces that it becomes larger and stronger when it consumes metal. To stop it, they need a large amount of xantronium, which blocks energy waves. They lure it to a building whose roof is made of xantronium; when it eats some, it shrinks back to a small size. Leonardo traps the creature in a supply shed, and leaves the words "Dregg Was Here" on it.
Meanwhile, Dregg is preparing to fire the laser cannon, and is about to vaporize New York when the generator overload and explode, causing the citadel to collapse. Dregg barely escapes, cursing the Turtles.
- Leonardo (Cam Clarke)
- Donatello (Barry Gordon)
- Raphael (Rob Paulsen)
- Michelangelo (Townsend Coleman)
- Carter (Bumper Robinson)
- HiTech (Rob Paulsen)
- Splinter (Peter Renaday)
- April O'Neil (Renae Jacobs)
- News Reporter (Townsend Coleman)
- Lord Dregg (Tony Jay)
- Dregg's Tannoy Voice (Renae Jacobs)
- Turtles' Lair
- City Streets
- Hydro-Dyne Chemical lab
- Carter's Motorcycle
Home media releases
- Teenage Mutant Ninja Turtles Season 9
- Teenage Mutant Ninja Turtles: The Complete Classic Series Collection
- First full appearance of the Turtles' super mutant forms.
- In the opening shot of the episode, the lettering on the front of the Turtle Van is black instead of white.
- The wanted poster for the Turtles has two Leonardos on it.
- Carter points to the giant egg's "blue" veins, which are actually red.
- When Dregg watches the Turtles approach the citadel in the Turtle Van, the lettering on the front of the van is black again.
- When Leonardo & Donatello get blasted through floor by Dregg's robot, a closeup shot of Leonardo's feet show him standing in front of a wall, but he isn't in the previous or next shot.
- When the Turtles and Carter are planning what to do with the monster, the lettering on the front of the Turtle Van is black once again, in two shots.
- How is metal armor and a cyborg eye part of Leonardo and Donatello's mutations?