In a sea-cave on Lovatt Island, just off the west coast of Scotland, a skeleton is found shackled to the rocks. A victim of unparalleled brutality, the skeleton seems to belong firmly in the past, and DI Marjory Fleming anticipates a straightforward case. But when a modern watch is discovered on the skeleton's wrist, Fleming realises the crime may be far closer to home.
Meanwhile, a series of escalating crimes arise in the nearby village of Innellan. The villagers, with their own enigmatic pasts, are reluctant to speak out. Fleming, sensing a pattern she cannot clearly discern, becomes increasingly desperate to prevent more violence. Are the skeleton and the current spate of crimes connected? If so, what evil act could have motivated such a deadly, merciless design?