"I know about Silver Key, the girl said. "I'm here to help you get your next power." Max has been waiting all summer for a clue that will tell him how to get his next superpower. When a mysterious girl turns up, things begin to move very fast! Who are the Guardians and where are they? What danger is lurking around the Silver Rock hide-out? And can Max find out before it's too late? With his sister Bea and best friend Corky in tow, Max must find the Guardians, get his next power and with the help of a friendly whale, save the Silver Rock from a gigantic slimy villain…!