The Turtles and Splinter are visiting London's British Museum, and study a portrait of King Arthur, Queen Guinevere and the Knights of the Round Table. In Dimension X, Krang is using a long-range scanner and discovers a rare metal buried in a ruined castle in England.

After a fight with Shredder causes Donatello to be struck by a laser beam, his personality changes to become a costumed superhero known as the Dark Turtle. His mission: Seek out & destroy Shredder. Meanwhile, a dinosaur-like alien race called Triceratons, invades Earth.