Minor Mitchell, but Fun 
 "Tonight feels like a board game co-designed by M. C. Escher on a bender and Stephen King in a fever." This remark by one in the bewildered characters in Mitchell's spooky fantasy might well apply to the entire book. You get a strong hint of Escher in the curious peep-through cover (perhaps only in the hard-bound edition), and King is only one of the masters of the paranormal to whom Mitchell tips his hat. But beyond that, the comparison is pointless. As you could imagine of a book issued originally as a series of tweets, Mitchell does not intend to scare or bewilder his readers, merely invite them into a shared game. This is no more intended as a major contribution to Mitchell's oeuvre than 
 The Strange Library 
 was for Haruki Murakami, or 
 The Final Solution 
 for Michael Chabon. But a minor work by any of these great authors is still a book written by a master, no matter how far he lets down his hair. 
 Like Platform 93/4 in Harry Potter, Slade House can only be found when the time is ripe, by penetrating a narrow alley twisting between high walls and opening a small black iron door set into the brickwork. Once in, however, the guest sees a terraced English garden with a splendid mansion at the end of it, a house with many rooms and a grand staircase lined with portraits that seem to change at each visit. It is a while before we notice anything amiss. The first visitors, in 1979, are a concert pianist and her precocious thirteen-year-old son. In the next section, we are in 1988, and the visitor is a Thames Valley Police detective investigating a cold-case disappearance, but also seduced by the delights of the flesh. Nine years on again, in 1997, it is the Paranormal Society of the local university (Reading, I imagine). And so to 2006 and 2015; the nine-year cycles will ultimately be explained in a later section, which could be open to the criticism of offering too much postponed exposition too late. 
 No, this is not my genre, and I would not have picked it up were it not for Mitchell. But as a Brit myself, I know and like his people, I know their language, I once shared their concerns. And as always with Mitchell, I enjoy his habit of paying homage to character types from the popular fiction I read when young: the brilliant child, the detective, the lonely outcast, the young woman on her way up. Yes, these are cliches, but that is precisely why Mitchell uses them: he is creating a world from familiar materials, and then playing games with them. Were it not the term too academic for the Young Adult feel (and intent?) of the book, I would call it metafiction. And, as in all his novels except the first, he is equally free in referencing his own work. If this is your first Mitchell, you won't notice anything, but many of the names tie in with characters, events, and places in everything from 
 Cloud Atlas 
 to The Bone Clocks, and perhaps even earlier. 
 I always enjoy spending time with Mitchell, his humanity, and his humor, and this was no exception. But unless suggesting something for a bright young teenager, I would not start here. Look for him where he is really doing some heavy lifting, as in The Thousand Autumns of Jacob de Zoet, my personal favorite.