The Room with Eight Windows — Jane A. Adams

Henry Johnstone has retired from the police, but when he suddenly disappears his old colleague and friend, Inspector Mickey Hitchens, investigates.

December, 1930. Henry Johnstone has retired from his role as detective chief inspector at London's Scotland Yard and is staying at the home of the late Sir Eamon Barry on the south coast, cataloguing and inventorying his extensive library. Until he suddenly â€" and inexplicably â€" vanishes.

Mickey Hitchens, Henry's old partner-in-crime, now an inspector himself, investigates the house with his colleague, Sergeant Tibbs. The room Henry was staying in had eight unusual, curved windows, and the pair quickly uncover disturbing signs of a struggle, along with a blotter that has the name of a man who was murdered five years ago written on it. Is there a link between that case and Henry's disappearance? Can Mickey find his friend and bring him home safely, or is it already too late?