Sarah Pinborough seems to be taking a social media break, probably to get on with writing marvellous books, so I can sneak in and say that The Death House is absolutely freaking awesome without getting all embarrassed about being fanboyish, and also without letting on that it took me six months to get round to reading it.
Stephen King thinks it's awesome, so my tuppence is hardly required, but anyway. It's a great book that needs bracketing alongside The Lion The Witch & The Wardrobe, The Hobbit, and particularly Lord of the Flies as a timeless children's classic (or YA, whatever, but that wasn't really a thing when the other three were written).
From a writering point of view, world-building obsessives should take note of the highly broad strokes with which Pinborough paints the society and sequence of events that leads to the young Defectives being sent away to the Death House, and its mysteries that are never entirely solved. As with Lord of the Flies, from which this technique is most obviously familiar, the story is everything, and wider exposition is dripped in miserly doses only when it's absolutely necessary.
And what a story. Pinborough is a former teacher, and as William Golding proved with Lord of the Flies, that does seem to help creating truly realistic adolescent characters. As the cast of children while away their days waiting for their symptoms to develop, the conflicts, bonds, lies and coping mechanisms all ring true.
And the ending, oh dear. Certain plot developments are abundantly clear to readers, long before the characters catch on, reinforcing the idea that we're reading about frightened and confused children who are forced to pretend to be adults as they confront their mortality. In spite of me being Mr Smuggypants Smug Reader, however, the closing chapters quite simply blew me away, and I cried. And I don't cry at books. Or anything. 22 August 2015 was a baking hot day in the UK, so it was just eye-sweat, I tell you.
Do yourself a favour and get hold of it in whichever format you think you prefer: The Death House.