Fionn Boyle has been the Storm Keeper of Arranmore for less than six months when the island begins to fail. Illness seeps across the land, giving rise to widespread fear and suspicion, but Fionn is powerless to help. The Storm Keeper's magic has deserted him. Even his sister Tara has more control over the island than he does, and she won't let him forget it. Worse still, his grandfather's candle - the one that roots his memory in the here and now - is burning low. Fionn and Malachy Boyle are both running out of time. When the evil sorceress Morrigan's soul stalkers begin to return, Fionn must find a way to summon Dagda's army of merrows to protect the island. But how can he call upon a vast number of ferocious sea creatures without any magic? Or the faintest idea of where to look for them? The race to save Arranmore has begun.