The 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 . . .

P.S. Beware of pirated copies of important books (with missing sections) circulating online.