Blue Hour - By Paula Hawkins

WELCOME TO ERIS - A SCOTTISH TIDAL ISLAND WITH ONLY ONE HOUSE, ONE INHABITANT, ONE WAY OUT. . . A place that is unreachable from the Scottish mainland for twelve hours each day. Once the hideaway of Vanessa, a famous artist whose notoriously unfaithful husband disappeared twenty years ago. Now home to Grace. A solitary creature of the tides, content in her own isolation. But when a shocking discovery is made in an art gallery far away in London, Grace receives an unexpected visitor. And the secrets of Eris threaten to emerge . . .