An atmospheric and often deeply creepy interpretation of water horse folklore. Honestly I felt more for the two featured horses (Dove and Corr) than I did for their human riders, but the real star of this book is the island of Thisby. It's a sort of modern-ancient mix of grudgingly updated tradition and blood, and it felt absolutely real to me, especially in the various and often conflicting ways in which the humans adapted themselves to the phenomenon of the horses. Really, the world-building was excellent and I don't say that often. Never did it get in the way of the story, rather it illuminated it. If only more fantasy authors showed such competence and restraint.