After going through the door that called to them both in dreams, Emory and Romie find themselves in the Wychwood, albeit a twisted, rotting version of it that feels wrong. Meanwhile, tensions flare at Aldryn College when the truth about Collapsings comes to light, sparking rumours of the Shadow's imminent return. Determined to cross into the Deep, Baz and Kai go through the door - only to be pulled back in time instead. Across time and worlds, the four friends find their fates eerily interwoven with those of the heroes from Clover's book. But when they encounter a deadlier enemy than they ever thought possible, they must decide for themselves how their story will end. Opening locked doors has a price - even for those who hold a key.