After being kicked out of Fillory, Quentin spent some time teaching at Brakebill's, until he was kicked out of there, too. Now he's working a heist to pay his bills and keep doing magic. Meanwhile, Ember has told the kings and queens of Fillory that the end of the world is at hand, and they're desperately searching for a way to prevent it. Everything is connected, and everything comes full circle in the last of the Magicians trilogy. 
 There's a lot going on in this book--I mean a lot--and a re-read will definitely be in order before I can really articulate all the thoughts I have about it. Grossman continues riffing on high fantasy, specifically Harry Potter and The Chronicles of Narnia (though some obvious, if minor, references are made to Discworld, The Lord of the Rings, and Neverending Story). In The Magician's Land, Grossman goes full The Last Battle, tearing Fillory down to its very essence. While the other books have seemed to primarily comment on adults outgrowing children's and YA fantasy, The Magician's Land appears more interested in questions of religion and philosophy; Grossman's "Last Battle" isn't a grand, allegorical battle, but a chaotic, almost pointless free-for-all in the face of impending annihilation. The way that Ember and Umber handle that annihilation--as well as the way Quentin ultimately handles it--is more the point than recreating any one religion's beliefs about the end of the world. 
 Despite the previous books' insistence on adults needing to let go of childish things--like Narnia/Fillory--the end of The Magician's Land is much more Tolkienian in the sense that escapism can be good and even healthy as long as it's not taken to extremes. The world is the world and it must be dealt with, but wanting to be a better person and wanting to live in a better place is not psychologically unhealthy. 
 I'll definitely be re-reading the entire trilogy and most likely writing (and hopefully publishing!) a full-length paper on all these questions/observations.