Lord Dregg has managed to open a gigantic portal that is large enough to pull the entire Earth into Dimension X. While trying to figure out how to stop it, Leonardo, Donatello and Master Splinter are pulled through the portal, after Dregg turns the portal on them. watch
While Raphael, Michelangelo, Donatello and Carter work on restoring Leonardo to his regular self, Mung steals all the plutonium from a power plant in order for Dregg to build a Plutonium Ray to turn Leonardo into a radioactive killer. watch
After re-energizing the present-day Turtles, the Turtles of the past have only 3 hours to get back to their time, or they will all cease to exist. Meanwhile, during the 15 hours it took to re-energize the Turtles, the remainder of Dregg's invasion fleet has been completed and has been unleashed on the city and now the Turtles and Carter have to stop Dregg, Krang, and Shredder. In the end Shredder and Krang are sent back to Dimension X, and after sending the past turtles back to their time, Landor and Merrick give Carter an offer to come with them to their time in the future to receive medical treatment that will completely cure him of his mutation. Carter accepts and he and the turtles say their goodbyes before he teleports away. watch