This is one of the most original stories I've read in a long time. Ms. Stiefvater has developed a world that is both fascinating, and somewhat terrifying. The isle of Thisby, surrounded by a dark and violent sea, is where the water horses, the capaill uisce, come to land. They are beautiful, strong, fast, and fierce. If captured, they can be trained to race in the big race on 1 November—a day someone will die. What they want, more than anything, is the sea—and to kill and eat their rider.
This story is told through two points of view—that of Puck, the first girl to enter the race and on an island pony instead of a capall uisce, and the young man, Sean and his beloved water horse, Corr. (note: capaill uisce is the plural)
Puck, along with her two brothers, are orphans, and she enters the race as the only means of getting enough money at one time, to pay off the only home she has ever known, or face eviction. She is not wanted on the beach of sand where the race will be held. The race is dangerous, and it is a man's game, and no upstart girl is going to buck tradition.
Sean is the odds on favorite to win the race. Riding Corr, the water horse of his employer for the last four years, he has won. He wants to buy Corr, but his owner refuses. He wants to win the race and enough money to make the purchase, against all odds. He has warned Puck to keep herself and her 'pony' off the beach.
None of the capaill uisce turn into nice, loving horses, or charming dark-eyed men. They want meat and blood, and humans qualify. They want the sea, and any rider who thwarts their return, faces death. Puck faces not only her death, but also the prospect that her beloved Dove will also die. But home is worth dying for.
Thisby is a world rich in atmosphere and characters. The people live on a hard land, and are somewhat taciturn. The reader will get to know them not so much through their words, but the eyes of those who see them. Salt spray covers everything, the clouds hang low in the sky, blood soaks the sands, and never, ever, run from a capall uisce, for they are predators at the top of the food chain.