- When Fionn Boyle sets foot on Arranmore Island, it begins to stir beneath his feet. Once in a generation, the island chooses a new Storm Keeper - someone to wield its power and keep its magic safe from enemies. The time has finally come for Fionn's grandfather, a secretive and eccentric old man, to step down. Soon, a new Keeper will rise. Fionn's ancestral home has been waiting for him. But deep underground, someone else has been waiting, too. As a battle rages, over who will become the island's next champion, a more sinister magic is waking up, intent on rekindling an ancient war.