On a cool June morning, a woman is walking her dog in the idyllic coastal village of Salten along a tidal estuary known as the Reach. Before she can stop him, the dog charges into the water to retrieve what first appears to be a wayward stick, but to her horror, turns out to be something much more sinister. The next morning, three women in and around London -- Fatima, Thea, and Isabel -- receive the text they had always hoped would never come, from...