Every year, a small group of acquaintances pay a visit to the remote, castle-like Water Mill House, home to the reclusive Fujinuma Kiichi, son of a famous artist, who has lived his life behind a rubber mask ever since a disfiguring car accident. This year, however, the visit is disrupted by an impossible disappearance, the theft of a painting and a series of baffling murders.

The brilliant Kiyoshi Shimada arrives to investigate. But will he uncover the truth, and will you be able to solve the mystery of the Water Mill House Murders before he does?