The Causeway — P.M. Hubbard

Peter Grant, sailing his boat in unfamiliar waters, is forced ashore on an island connected with the mainland by a causeway uncovered only at low tide. There is a house on the opposite shore lived in by two secretive people.

His involvement in their affairs, begun by his sea-chance, becomes deeper and more dangerous as the tides ebb and flow over the causeway, until he finds himself face-to-face first with love - and then with terror and violent death.

'A sensitive, absorbing tale' Sunday Times