The addictive million-copy bestseller mystery taking Japan by storm, from the author of The Times Bestseller Strange PicturesA twisty puzzle in which the reader is the detective, examining a series of creepy floorplans for clues. A sinister hidden room. A dead space between two walls. A sealed cellar.

A child's face glimpsed at a window. Every house hides secrets. But some secrets are far darker than others.

More than a million readers have discovered the terrible truth behind these strange houses. Now it's your turn.