Shinji Takahashi has learned a lot as a member of the Society of Explorers and Adventurers--like how to scale a cliff with nothing but some rope and good luck, or how to outsmart a serpent warrior in the middle of the jungle. One thing he hasn't learned, however, is how to control his newfound guardian magic, or what this magic means for him.

After 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 and his friends head off to check out the wreckage, hoping to get there before the Hightower Corporation can plunder the site.

But when Shinji accidentally awakens a guardian who's been trapped inside a volcano for a century, it 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.

To do so, he must head into the heart of the storm.