London, 1976. In the thick of a record-breaking heatwave, Gretta Riordan’s newly-retired husband has cleaned out his bank account and vanished. Now, for the first time in years, Gretta calls her children home : Michael Francis, a history teacher whose marriage is failing; Monica, whose blighted past that has driven a wedge between her and her younger sister; and Aoife, the youngest, whose new life in Manhattan is elaborately arranged to conceal a devastating secret.        In a story that stretches from the Upper West Side to a village on the coast of Ireland, Maggie O’Farrell explores the mysteries that inhere within families, and reveals the fault lines over which we build our lives. Instructions for a Heatwave weaves an unforgettable narrative of a family falling apart and coming together with hard-won, life-changing truths about who they really are.