Shredder, Bebop, and Rocksteady are in town to steal a rare new mutagen created by Oswald Dren, a grad student. Some mutagen is accidentally spilled onto a reel of movie film and monsters and a movie hero named Rondo come to life! The real Rondo is a wimp, and the Turtles try to help him confront the now-living monsters that stalk the street and the movie theater where the Monster Movie Marathon took place. With the turtles' help, Shredder and the mutants fail to steal the mutagen.