After a mysterious school opens across the street, the girls of Super Hero High find themselves up against a new threat. Now, Supergirl, Wonder Woman, Batgirl, and the rest of the Super Hero Girls have to worry about not only the well-being of their grades but also the safety and security of friends, family, and the rest of civilisation. The girls must figure out how to put a stop to this evil new rival and save the world once again!