On holiday with Captain Hastings on the Cornish coast, Hercule Poirot insists he has retired from detection and has set aside an urgent appeal from the Home Secretary. His resolve falters when he meets Magdala "Nick" Buckley, the spirited young owner of a crumbling clifftop house near the seaside town of St Loo. Over a few short days she has survived three brushes with death: failed car brakes on a steep hillside, a boulder that crashed past her on a coastal path, and a heavy picture that fell on the bed where she should have been sleeping. She treats them as bad luck. When Poirot finds a bullet hole through the brim of her hat, he is certain someone is trying to kill her. Convinced a murder is imminent rather than already committed, he sets out to guard her and to map the circle of people around her: an old school friend, a navy commander, an art dealer, a watchful solicitor cousin, and a relative who comes to stay. Hastings narrates as Poirot weighs motives of money, love, and debt, testing each version of events against the small, stubborn facts. The seemingly senseless attempts resist every neat explanation, and the closer Poirot looks, the more the danger refuses to stay where it seems to belong.