The Shredder Strikes Back, Part 1.During an early morning training run, Leonardo encounters a legion of Foot Ninja and Hun. A thunderstorm develops not long before Leo encounters a new foe, the Foot Elite. As he becomes overwhelmed, Leo witnesses the return of an unexpected enemy: the Shredder. After being thrown through a window into April's apartment, Leonardo lies unconscious while his brothers and Master Splinter defend against waves of attacking Foot Ninja. Desiring revenge, the Shredder seeks to destroy the Turtles and their allies at any cost. As the Turtles and their allies are retreating, Shredder blows up the building.