The original Shredder is resurrected by the Foot Mystics, whose first agenda is to destroy Karai – the “false Shredder.” And, while the Turtles are enemies of both Shredders, they realize that if the original Shredder wins, his goal of creating a world of destruction, devastation and chaos will be one huge step closer to reality. So, like it or not, they have to help Karai – even while she’s intent on killing them!