The Survivors by Jane Harper

Kieran Elliott's life changed forever on the day a reckless mistake led to devastating consequences. The guilt that still haunts him resurfaces during a visit with his young family to the small coastal community he once called home. Kieran's parents are struggling in a town where fortunes are forged by the sea. Between them all is his absent brother, Finn. When a body is discovered on the beach, long-held secrets threaten to emerge. A sunken wreck, a missing girl, and questions that have never washed away...