The Hollow Places - T. Kingfisher

Carrot has moved into the Wonder Museum - an eclectic collection of taxidermy, shrunken heads, and Mystery Junk owned by her Uncle Earl. For Carrot, it's not creepy at all: she grew up with it. What's creepy is the corridor behind one of the museum walls. There's just no space for a corridor there – or the concrete bunker, or the strange islands beyond the bunker's doors, or the unseen things in the willow trees.

Carrot has stumbled into a horrifying world, and They are watching her. Strewn among the islands are the remains of Their meals – and Their experiments. And even if she manages to make it home, she can't stop calling Them after her… 

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