Murder at the Loch — Eric Brown

Crime writer sleuth Donald Langham is invited to a remote Scottish castle to solve an intriguing mystery.

It's the bitterly cold December of 1955, and Donald Langham has been asked by his friend, private detective Ralph Ryland, to assist him on a case. Ryland has been contacted by their old commanding officer, Major Cartwright, who has reasons to believe that his life is under threat at his remote castle in the Scottish Highlands.

On arriving at the castle, Langham and Ryland learn that Major Cartwright is attempting to raise the wreck of a German fighter plane which crashed into the loch in 1945. But it's not only the bad weather that has put a halt to the progress of the salvage. Soon after Langham's arrival, one of Cartwright's guests is brutally murdered -- and the hunt is on to stop a ruthless killer before he -- or she -- strikes again!