Carter, April and the "past" Turtles are being attacked by monsters towering fifty feet over them. The heroes finally escape and get the weakened "present" Turtles back to the lair. April heads off to warn the authorities of Lord Dregg's attack plan.
Dregg and his crew plan an invasion of Attack Monsters to take over Earth and make it his new home base, but first he has to get his transporter chip back from Shredder...
Meanwhile Krang and Shredder free themselves from the rubble of the caved-in building and head back to the nuclear power plant. They run into a patrol of bat-men, but Krang successfully hypnotizes one of them, and they continue on their way.
Back at the Turtles' lair, the weakened Turtles are revived. The "past" Turtles want to get home. Carter sends out a message to Landor and Merrik to take the Turtles back to the past but he gets no response. Donatello reminds them that the "past" Turtles can only remain for a short while or all eight Turtles will cease to exist!
Dregg reveals that he needs most of his bat-men to man his Attack Monsters. He also has his micro-bots construct weapons for the Monsters and sets them out to attack the Earth.
Back at the lair, Landor and Merrik materialize only to find that the "past" Turtles went to battle the Attack Monsters. They go off to find them.
Carter and the "present" Turtles arrive at the power plant and battle Dregg and the remaining bat-men. During the battle, Dregg goes after Shredder, hoping to get the chip back. Donatello is knocked into the computer and he quickly does some rewiring. Dregg traps Shredder, Krang, Carter and the Turtles and gets the chip! He puts in into the transporter and orders Mung to transport a sunspot to the nation's capital. Mung throws the switch and on the screen you can see the capital burn. Dregg watches as more sunspots are being transported to cities around the world.
In the City the "past" Leonardo discovers that there are bat-men inside the Attack Monsters. The Turtles are able to get inside one and use it to take out all the other Attack Monsters. They head for the power plant in their Attack Monster.
Dregg calls the UN demanding they surrender the world to him or he will turn the entire planet into a boiling sun. The UN official does not know what on Earth Dregg is talking about. Dregg is enraged. He checks his computer and discovers he's got a bogus chip. Donatello reveals that he rewired the computer to play Dregg's VR simulation of the sunspots.
Dregg is furious. He aims his wrist blaster and is about to start shooting when the "past" Turtles arrive in the Attack Monster. The other Turtles finally capture Dregg and drain him of his Krang/Turtle energy. They transport Shredder and Krang back to Dimension X, and transport Dregg and Mung back to their home planet. Landor and Merrik arrive and take the "past" Turtles back to their own time. They also extend an offer to have Carter travel with them to the future so the scientists there can cure him. Despite some hesitation, Donatello agrees that Carter should go since they do not have the resources to cure him completely in the present. After Raphael and Michelangelo remind Carter about not bringing any Ninja Turtles from the future, Carter says "See you in the Future" and immediately teleports with Landor and Merrik.
- Leonardo (Cam Clarke)
- Donatello (Barry Gordon)
- Raphael (Michael Gough)
- Michelangelo (Townsend Coleman)
- Splinter (Peter Renaday)
- April O'Neil (Renae Jacobs)
- Carter (Bumper Robinson)
- Lord Dregg (Tony Jay)
- Mung (Cam Clarke)
- Shredder (Bill Martin)
- Krang (Pat Fraley)
Home media releases
- Teenage Mutant Ninja Turtles: The Complete Final Season
- Teenage Mutant Ninja Turtles: The Complete Classic Series Collection
- In the episode's recap, on the security footage of Shredder stealing the Subspace Amplification Chip he's stealing it from a completely different machine. In fact, it's actually footage that's used later in the episode.
- When all eight of the Turtles return to the lair and the future Donatello helps the past Donatello sit down, past Donatello's belt letter is missing.
- When Carter fires up the Demutation Ray, the button he presses has another button underneath it.
- Right after Carter mutates, saves the Turtles from Dregg's robots, and demutates, they ask if he's okay. His mouth doesn't move when he answers.
- This is the last episode to feature Shredder, Krang, and Carter.
- In the previous episode, Krang loses his bubble walker, but he has it back in this episode.