When he finds poison in the Black's stable, Alec suspects someone is trying to kill his beloved stallion. But just as he's puzzling over the clues, something even more disturbing happens. An Arab chieftain shows up and reclaims the Black.

When his wild black stallion revolts against the routine and schedule of stable life, becoming a killer and a threat, a plane crash thwarts Alec's plans to give the Black a free run in the desert and brings danger to both boy and horse.

Two visitors from another world enter the secret valley of Azul Island and provide Steve with a chance to see how Flame can do in competition with the world's fastest horses.