The Lighthouse by P.D. James

A secure and secluded retreat for the rich and powerful becomes the setting for an unsettling series of murders.Combe Island off the Cornish coast is a restful haven for the elite. But when one of its distinguished visitors is found hanging from the island’s famous lighthouse in what appears to have been a murder, the peace is shattered. Commander Adam Dalgliesh is called in to handle the sensitive case, but at a difficult time for him and his depleted team. He is uncertain about his future with his girlfriend Emma Lavenham; his principle detective Kate Miskin is going through an emotional crisis; and the ambitious Sergeant Francis Benton-Smith is not happy about having a female boss. After a second brutal killing, the whole investigation is jeopardized, and Dalgliesh is faced with a danger even more insidious than murder.