In their underground lair deep beneath the city streets, in the middle of an intense training session, the Turtles and Master Splinter are suddenly attacked by a horde of Mouser robots! These mechanical menaces chomp through everything: stone, steel… Turtles! In the course of the battle, the Mousers cause the roof of the Turtles’ sewer-lair to cave in, separating our heroes from their beloved Master. Now the Turtles must abandon their home of 15 years and find their missing Master. But on the way, they have to deal with collapsed sewer tunnels, the Purple Dragon street gang, and a small army of mysterious, highly trained Ninja!