What the Tide Kept. A Claire Harmon Mystery, #11

When Will's restoration crew tears open a sealed wall in the boathouse wing of a granite family house on England's Isles of Scilly, they find something that should have drowned with a man forty years ago - and within days, the past has claimed a second victim. Claire Harmon and her husband Will have crossed to the remote island of Tresco so he can restore the Pengelly family's ancestral home, Carn Near House.
She expects a quiet working holiday. Instead she gets a house full of secrets, a family that flinches every time a decades-old wreck-diving death comes up, and - within days of the wall's discovery - the drowned body of the family's own archivist on the tidal sandbar below the house. With a summer storm grounding every flight and boat off the island, Claire is stuck inside Carn Near House with everyone who might have wanted the truth to stay buried: a mother whose alibi is suspiciously vague, a golden-boy grandson a little too calm for a man who's just lost his sister, and a ninety-one-year-old grandfather whose story about that long-ago drowning has never once changed in forty years - which, Claire has learned the hard way, is exactly the kind of story that usually isn't true.
Perfect for fans of Ann Cleeves, Lucy Foley, and Elly Griffiths.