As Shinji struggles to understand and control his new guardian magic, the members of S.E.A. learn that a sunken ship belonging to the long extinct Natia people has been found on the floor of the Pacific Ocean. Shinji, Lucy and Tinker, along with Oliver Ocean and Phoebe Mystic, a quirky, enthusiastic magic expert who has been called in to help Shinji, head off to check out the wreckage, hoping to get there before the Hightower Corporation can plunder the site, and picking up a young stowaway by the name of Roux along the way.

But nothing goes as planned, and when Shinji accidentally awakens a guardian who's been hidden on a mysterious island and trapped inside a volcano for a century, he causes a volcanic eruption and releases a massive hurricane that threatens the entire coast of California. Now Shinji must learn to control his powers and best his fears so that he can stop the destruction and regain the trust of S.E.A before it's too late.