The global No.1 bestselling author of The Girl on the Train invites you into her most suspenseful and powerful thriller yet.

Eris, an island with only one house, one inhabitant, one way out. Unreachable from the Scottish mainland for twelve hours each day.

Once home to 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, a visitor comes calling.

And the secrets of Eris threaten to emerge . . .

‘Extremely hard to put down.’ – Mick Herron

‘The Blue Hour swept me along on a tide as unforgiving and irresistible as the one around the island of Eris.’ – Val McDermid