The Black Stallion and Flame by Walter Farley

While flying to a race, Alec Ramsay and the Black's plane crash-lands in the stormy Caribbean. Chance brings the Black to the hidden island home of the giant red stallion, Flame. Such a small island can only support one alpha male. But before the two can fight-a fight that can only result in the death of one-a new danger appears. Together, can the stallions defeat the deadly foe which threatens the lives of the entire herd of wild horses?