Welcome to Eris: an island with only one house, one inhabitant, one way out. Unreachable from the Scottish mainland for 12 hours each day. Once home to Vanessa, a famous artist whose notoriously unfaithful husband disappeared 20 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, a visitor comes calling. And the secrets of Eris threaten to emerge.