The Ninja Turtles are going out of this world. Way out! Their arch villain Shredder has concocted two new mutants and a gigantic robot to destroy the turtles. But also, a mysterious, two foot fifth turtle is following the four around. His name is Kerma and he's from Shellrelah, a turtle world. Well while the turtles are called on to help the turtle world in distress, Shredder is left to do his worst on the city. Can the green teens help their fellow alien turtles and save the city?