No Mans Island by Susan Sallis
When news of the death of her ex-husband reaches Binnie, it seems that her tranquil life in the West Country would come to an end. To her surprise, she discovers that he had left her the island in the beautiful archipelago off the coast of Cornwall where he had spent his childhood, and Binnie has to take her family to the island - revisiting it for the first time in years - and work out what to do. Leaving behind the mysterious stranger who had turned up in the village only the day before, Binnie has to embark upon a whole new life and come to terms with a dark past.