A new threat has come to the Monster world, this one bigger than ever. Nine Monsters, stronger, faster and more evil have awakened, determined to destroy the human race. They are seemingly unstoppable, until Shay and Stella take on the challenges awaitening. Together, they search for the Knights of the Sky, Monsters that have been long forgotten, and attempt to stop the Generals before it's too late. Before the government commits its plan to save humans. Before it wipes out all Monsters from existence.