The Turtles are making their way through a strange maze of deadly traps and alien creatures, which turns out to be a nightmare of Michelangelo's. He becomes convinced that they won't make it through their next battle.
Meanwhile, Mung tells Lord Dregg that he has encountered Krang and Shredder in Dimension X, and that they battled the Turtles for several years.
Donatello tells Carter that he may have formulated a cure for Carter's mutation, and after some indecision, Carter decides that he wants to be cured after all and return to college.
Dregg temporarily blacks out all of New York in order to teleport Krang and Shredder out of Dimension X. April is caught in a falling elevator, Carter must stop a runaway streetcar, and the Turtles and Splinter are washed out of their lair and down into a whirlpool.
Shredder and Krang aren't very enthusiastic about Dregg's offer of mutual global domination, since they are interested in destroying the Turtles themselves. They're chased into April's car by one of Dregg's minions, and she quickly contacts the Turtles to notify them that Shredder and Krang have returned.
Fortunately the Turtles have been washed out of the sewer by then, and are able to get a taxi to take them on a wild car chase where they fight with Shredder. However, the cars are teleported away by Dregg, resulting in a chaotic fight in which the Turtles must fight both Dregg's forces AND their old nemeses. Dregg eventually convinces a reluctant Shredder to join his side, but Donatello beams up a large amount of water from the flooded lair to temporarily disarm their enemies.
However, Leonardo is captured when he tries to prevent a nuclear meltdown, and the Turtles and April end up at their enemies' mercy. Dregg reveals that he wanted them to stabilize their mutations so he could use them for his own ends: he's draining them of their mutagenic life force so he can use it for himself.
Unsurprisingly Shredder turns against Dregg again, and demands that Mung transfuse the life energy into himself and Krang instead. But Dregg looses some microbes which successfully immobilize Shredder and Krang by transforming Shredder;s armor and Krang's walker. Dregg decides to also take Krang's formidable intelligence for himself, growing larger and more powerful even as the Turtles seem to be going critical. Michelangelo begins mumbling about his dream.
- Leonardo (Cam Clarke)
- Donatello (Barry Gordon)
- Raphael (Michael Gough)
- Michelangelo (Townsend Coleman)
- April O'Neil (Renae Jacobs)
- Carter (Bumper Robinson)
- Lord Dregg (Tony Jay)
- Shredder (Bill Martin)
- Krang (Pat Fraley)
- Mung (Cam Clarke)
- Cab Driver (Pat Fraley)
- April's Sports Car
- Taxi Cab
Home media releases
- Teenage Mutant Ninja Turtles: The Complete Final Season
- Teenage Mutant Ninja Turtles: The Complete Classic Series Collection
- At the Newspan building, the elevator button that April presses flashes red, but the red light doesn't come out of the button; it comes on next to it.
- The interior of April's car is gray, but in one shot of Shredder and Krang when Raphael and Leonardo jump onto roof, the interior is yellow.
- In April's car, Shredder is sitting behind April and Krang is sitting behind the passenger seat. After Dregg beams them to his lair, Krang is sitting behind April and Shredder is sitting in the passenger seat.
- When the Turtles are tied up by Dregg to have their life sources drained, they are lined up in the following order from left to right - Raphael, Donatello, Leonardo and Michelangelo. But when Michelangelo speaks, he is suddenly next to Raphael.
- Splinter surprises the Turtles when they're looking for him... even though they're depicted as looking in the general direction where he was sitting.
- First appearance of Shredder and Krang since "Turtle Trek".
- The sound effect for the vortex transporter in this episode included the sound effect of the transporters in Star Trek: The Motion Picture