Quentin, Julia, Eliot and Janet are established as the kings and queens of the magical land of Fillory after their harrowing adventures in the first book in this trilogy, The Magicians. It is well worth reading or re-reading the first book because there are many references to specific occurrences from it. The first book set up the story of our anti-hero, Quentin, and how he goes from a depressed introvert in Brooklyn to being a student at an exclusive school for magic. (Yes, it's a bit like Harry Potter, but it is decidedly darker). In this second book, Quentin finds the life of a magician king to be a bit boring. He longs for the days of danger and adventure. When trouble shows up, the others are content to leave it be, but Quentin jumps head-long into the depths of peril, while being forced to face his past and his inner self.
There is not quite the happy ending in The Magician King that there was in the first book, but if there is meant to be a third, that makes sense. It is a bit of a cliff-hanger. I have read reviews on both sides of the fence about this one. No one seems to be neutral about this book. You either love it or hate it. I couldn't stop reading it and I closed it thinking, "I can't wait for the next one!"