In a sea-cave on Lovatt Island, just off the west coast of Scotland, a skeleton is found shackled to the rocks. Although the apparent victim of a crime of unparalleled brutality, the skeleton seems to belong firmly in the past. Detective Inspector Marjory Fleming, called in to investigate, anticipates a straightforward case unhampered by the pressures of time. But when a modern watch is discovered on the skeleton's wrist, Fleming realises the crime may be far closer to home than she initially assumed.

Meanwhile, in the nearby village of Innellan, mysterious events begin to occur. Matt Lovatt, eponymous owner of the island, is at the centre of a series of escalating crimes - could someone be targeting him? The villagers, members of a small and introverted community, are little help - many seem damaged by their own enigmatic pasts, and all are reluctant to speak out. Fleming, sensing a pattern she cannot clearly make out, 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?