After witnessing a living dinosaur wander in the city and disappear abruptly, the Turtles follow its tracks into a large hole, where they discover a shocking revelation: A cave where dinosaurs still roam. Meanwhile, Shredder and his mutant goons, Bebop and Rocksteady, are also there, but to collect a crystal needed by Krang to recharge the power cells of the Technodrome. The Turtles discover that the crystal is the source for all lifeforms inside the cave, and must get it back before they are all destroyed. (thetvdb.com)