In their underground lair deep beneath the city streets, the Turtles and Master Splinter are suddenly attacked by a horde of Mouser robots!

Raphael is a little cooped up underground with only his brothers and Master Splinter. When Raphael almost clobbers Michelangelo in some brotherly sparring, it's apparent that Raphael needs to get out ... let off a little steam. But when he meets up with Casey Jones, a vigilante erring a little to the right of justice, Raphael must face the reality of his own hothead ways...

On a nightly training run, the Turtles and Casey Jones break up a Purple Dragon robbery. One of the perps is Angel, a girl Casey knows from the neighborhood who's going through her initiation rites to become a Purple Dragon.