Instructions for a Heatwave by Maggie O'Farrell

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, the three Riordan children are converging on their childhood home: Michael Francis, a history teacher whose marriage is failing; Monica, with two stepdaughters who despise her and an ugly secret that has driven a wedge between her and the little sister she once adored; and Aoife (pronounced EE-fah), the youngest, whose new life in Manhattan is elaborately arranged to conceal her illiteracy. As the siblings track down clues to their father's disappearance, they also navigate rocky pasts and long-held secrets. Their search ultimately brings them to their ancestral village in Ireland, where the truth of their family's past is revealed.
Wise, lyrical, instantly engrossing, Instructions for a Heatwave is a richly satisfying page-turner from a writer of exceptional intelligence and grace.