No one who saw the pictures will ever forget the tsunami breaking over the shores of the Indian Ocean on Boxing Day 2004, uprooting trees, toppling buildings and pounding to death those caught in its wake. One of the survivors was a young economist called Sonali Deraniyagala, whose entire family was among the almost quarter of a million people who died. Wave, written eight years after the event, is a memoir about what it means to survive.

Deraniyagala, her husband, Steve, their two sons, eight-year-old Vikram and five-year-old Malli, and her parents were packing up to leave the resort of Yala, a national park on the southeastern coast of Sri Lanka where they had spent many happy holidays, when she happened to look out of the hotel