Angus and Sarah Moorcroft were the perfect upwardly mobile middle class couple, the envy of all their friends. Young, attractive and successful, and living with their identical twin daughters in a nice house in a desirable area of London. Then their world fell apart. One of their daughters, Lydia, died in an accident. Angus turned to drink and lost his job, while Sarah turned in on herself. We meet Angus and Sarah, and seven year old Kirstie, a year after the accident. They can no longer afford to live in London and are planning to relocate to a tiny tidal island Angus has inherited from his grandmother and live in the dilapidated cottage attached to the lighthouse there.
But if the tragedy has had a major impact on Angus and Sarah, its effect on Kirstie has been to leave her deeply disturbed. As a parent, how do you respond when your surviving identical twin claims that you have made a mistake, and she is actually Lydia? The girls were physically indistinguishable, and the only way Sarah knew it was Lydia who had died was because she found Kirstie calling Lydia's name after the accident. What if it was really Kirstie who had died and Lydia had changed identity as a reaction to the tragedy?
Much of the book is set on the fictional Eilean Torran, a tidal island off the Sleat Peninsula on the Isle of Skye. The author notes in their introduction that the resemblance to Eilean Sionnach, off Isleornsay on Skye, is no coincidence, and this adds a fascinating dimension to the book for anyone who has gazed across to the lighthouse and cottages that are such a feature in the majestic view from Isleornsay.
The "almost real" setting also adds considerably to the tension and the chill you feel as the book builds steadily to a conclusion whose details are the subject of some extremely artful misdirection by the author. Kirstie/Lydia finds herself increasingly alienated by her behaviour in her new school on Skye, and Sarah and Angus become increasingly estranged from one another. Then a winter storm blows up, trapping Sarah and her surviving daughter on the island. This is a book that raises the hairs on the back of your neck and keeps you guessing right to the very end. It is a highly entertaining and thought-provoking read, and the perfect antidote for anyone who ever thought it might be a nice idea to inherit a small offshore Scottish island from an elderly relative!