Cold Earth (Shetland Island #7) by Ann Cleeves

In the dark days of a Shetland winter, torrential rain triggers a landslide that crosses the main Lerwick-Sumburgh road and sweeps down to the sea.

At the burial of his old friend Magnus Tait, Jimmy Perez watches the flood of mud and peaty water smash through a croft house in its path. Everyone thinks the croft is uninhabited, but in the wreckage he finds the body of a dark-haired woman wearing a red silk dress.

In his mind, she shares his Mediterranean ancestry and soon he becomes obsessed with tracing her identity.

Then it emerges that she was already dead before the landslide hit the house. Perez knows he must find out who she was, and how she died.