The King of Shadows

It's January of 1704, and Matthew Corbett continues his mission to Italy, accompanied by Hudson Greathouse and former enemy Professor Fell. They seek Brazio Valeriani and information about the mirror created by his father, the sorcerer Ciro. Legend claims the mirror can be used to summon demons from beyond.
But fate has other plans for Matthew as their ship is disabled by a pod of whales, and they seek refuge on a secluded island. The islanders welcome them with a massive feast, but all is not what it seems. As the island pulls them deeper into its influence, the castaways struggle to maintain their grip on reality, even their very identity. Matthew must keep his wits about him and solve the mystery enshrouding the other side of the island, where an active volcano looms and a secretive creature lurks.
The King of Shadows is the eighth installment in bestselling author Robert McCammon's acclaimed series of historical thrillers featuring Matthew Corbett, a brave "problem-solver" who now faces a challenging foe that threatens to take over his most valuable resource: his own mind.