The idyllic peace of a remote Scottish anchorage is shattered by an explosion aboard a luxury cruiser, which kills the woman on board and brings to an abrupt end the restful holiday which Clio Marsh prescribed for her detective husband, Harry.

Was the wreck of the Skara Sun an accident? Was Alison MacAllister murdered by the penniless young man sailing with her? Or by the rich older one to whom she was married? The local police investigate. Harry Marsh investigates. No-one who knows Clio would expect her to mind her own business.

The savage beauty of the wild west coast forms a backdrop to, and ultimately plays its own role in the developing drama as Clio discovers that even deadly Corryvreckan can be a friend in the face of human treachery.