Cal McGill is a unique investigator and oceanographer who uses his expertise to locate things—and sometimes people—lost or missing at sea. His expertise could unravel the haunting mystery of why, 26 years ago on a remote Scottish beach, Megan Bates strode out into the cold ocean and let the waves wash her away. Megan's daughter, Violet Wells, was abandoned as a baby on the steps of a local hospital just hours before. As McGill is drawn into Violet's search for the truth, he encounters a coastal community divided by obsession and grief, and united only by a conviction that its secrets should stay buried.