A spiritual companion to Strange Pictures and a bestselling horror phenomenon in Japan —mysterious spaces, trap doors, windowless children's rooms . . . something is wrong with this house. Can you solve the "mystery" of its floor plan? A writer fascinated by the macabre is approached by an acquaintance who is considering purchasing a second-hand house in Tokyo. With its bright and spacious interior, the home seems perfect. But looking closer, the building’s floor plan reveals a mysterious "dead space” hidden between the walls. Seeking a second opinion, the writer shares the floor plan with an architect friend only to discover more “strange spaces” dotted across the house. What are these mysterious “strange spaces” and why do they exist—are they really there, or is there something off with the floor plan? Who is the home’s former resident who suddenly disappeared? The freelance writer and his architect friend can’t resist the challenge of solving the riddle of these puzzling floor plans . . . and the terrifying plot behind it all.