Over the Sea to Skye 
 As this novel opens, Sarah and Angus Moorcroft are selling their house in London and preparing to move to a disused lighthouse-keeper's cottage on "Eilean Torran" (Thunder Island) of the coast of Skye in the Inner Hebrides of Scotland. As it happens, I know and love that corner of Skye, with the jagged ridge of the Black Cuillin mountains dominating the western skyline and the stunning views over the Sound of Sleat to the mainland to the east. Clearly Tremayne loves it too, conjuring its wild beauty in evocative descriptions, strings of Gaelic names chanted like incantations, and even a dozen black and white photographs. She* makes no secret of the real island on which her Torran is based, and it is easy to go the the web and see those views in full color, even the whitewashed cottage in which most of the book is set. Tremayne (a pseudonym) is not a travel writer in her real life for nothing. 
 Apparently, she is also the mother* of two girls. And that is where her novel gets really creepy. For until a year before, Angus and Sarah had twin girls, Kirstie and Lydia. But Lydia's death in a fall from an upstairs window has almost destroyed the family: their move to the island is a last-ditch attempt to put the pieces back together and to start from scratch. And, despite the difficulty of bringing an almost ruined cottage back to life, it looks as though it might succeed. Until Kirstie asks them: "Why do you keep calling me Kirstie? I'm Lydia." 
 And so we are embarked on a psychological thriller that grabs hold immediately and never lets go. Is it possible they made a mistake and buried the wrong child? Or are these hallucinations to be expected when a twin loses her close sibling? What secrets are Angus and Sarah keeping from one another? What really happened on the day of the terrible accident? What does the surviving twin know that gives her such nightmares at night? When Sarah believes she sees or hears her lost daughter, is she going mad, or is this really a ghost story, enhanced by what the locals have always known to be a "thin place," with a more permeable membrane separating it from the spirit world? 
 All of these questions will come to play in the novel that follows. But at heart it is about the most basic of human relations. A mother desperate to help a lonely child whose schoolmates reject her because she is strange. A husband and wife grabbing each other for support, yet turning away as the sureties of their marriage begin to crumble. Two damaged people trying to keep their footing on a groundwork of shifting facts as unstable as the treacherous mud flats that connect their island to the shore at low tide. And all in that sublime setting! What is there not to like? 
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 *I now gather that the author is a man. I had assumed otherwise, because Sarah at least begins as a more attractive character than the alcoholic Angus, and the theme of motherhood is one of the better-developed elements in the book.