The Magician King

Meet Quentin Coldwater, king of the bizarre and wonderful land of Fillory. But he is getting restless: even in heaven a man needs a little adventure. So when a steward is murdered on a morning’s hunt Quentin gets exactly that. But this quest is like no other. What starts as a glorified cruise to faraway lands soon becomes the stuff of nightmares.
But Quentin was once a man from modern-day Earth, where he attended a secret college of sorcerers, and no matter how far he has strayed from his origins, he cannot escape the consequences of his own deeds...