Django hears about a mythical horse living in a place next to the Mexican border called the Vorbiden Valley. Those who posses the horse would be the greatest cowboy in the world. So he makes his way trough the Forbideen Valley when he heard about a evil demon that lives in the Valley called Gwangi. But he ignores and keep on his quest while killing some dumb Indians.
he arrives in the valley, to discover that the horse was in fact a Hyracotherium, a species of tiny horse and the great horse a Elasmotheriums, a species of elephant sized rhinos. Which were impossible to tame. But the worst is to come. Gwangi, the Allotyrannous shows up. Who wins?