The Magician's Land by Lev Grossman
'Dark, dangerous and full of twists' George R. R. Martin, author of Game of Thrones
Quentin Coldwater has lost everything. He has been cast out of the secret magical land of Fillory and now, friendless and broke, he returns to where his story began: Brakebills Preparatory College of Magic. But Quentin’s past soon catches up with him . . .
Meanwhile, Fillory’s magical barriers are failing, and barbarians from the north have invaded. To save their beloved world from extinction, Eliot and Janet, High King and Queen of Fillory, must embark on a final, dangerous quest.Quentin’s adventure takes him from Antarctica to the enchanted Neitherlands, where he finds old friends.
But all roads lead back to Fillory, where Quentin must put things right, or die trying.