After four ninja turtles are mutated by a mysterious alien substance, they must come out of the sewers to defend their city against forces of evil from both past and present.
The Teenage Mutant Ninja Turtles continue to explore the outside world with Master Splinter, as evil forces appear on the city's surface. This time, the Turtles face a new adversary called Kavaxas.
The Turtles face a double threat when Krang and Shredder team up, but the final shocking surprise occurs when dangerous materials are accidentally released into the city by the Turtles themselves.
In the fourth season of the series, the Turtles face Shredder's new deadly assassin, Kavaxas, along with Krang's plots, and discover more mysteries and strange adventures in new worlds.
In the fifth and final season of the series, after Slithering's death and Super Shredder's destruction, a villain decides to bring Shredder back, and the Teenage Mutant Ninja Turtles decide to confront him again.