Mayhem ensues as the Turtles face new dangerous mutants in a special double episode. Plus, the boys try LARPing, Karai finally realises the truth, mutant villains steal retro mutagen, and the city is invaded by a new mutant using living pizzas to attack!
Episodes Comprise: 13. The Manhattan Project (Part 1) 14. The Manhattan Project (Part 2) 15. Mazes and Mutants 16. The Lonely Mutation of Baxter Stockman 17. Newtralized! 18. Pizza Face 19. The Wrath of Tiger Claw