After being injured while racing in Ireland’s famous Foster Stakes, the Black and Alec head to the Irish coast to recuperate. While there, they are charmed by the pleasant people and intrigued by tales of the kelpie, a shape-shifting creature of myth who carries unsuspecting riders off to a watery grave. Alec meets a lonely local girl, Mora, who has found a stray pony. Alec, recognizing her love of horses, teaches her to ride. But when Mora disappears, Alec realizes that she has been carried off by the mythical kelpie. Now, Alec and the Black must race the shape-shifter, not realizing that if they lose, not only will Mora be lost forever, but so will the Black.