Of all the ways Britain's ancestors have left their mark on the land, none are as impressive or as baffling as the giant carvings cut into the chalklands of Southern England. Chief among them is a White Horse, a 360-foot, mysterious piece of land art steeped in legend, folklore, and magic. Join Clive and Mary-Ann as they translate the subtleties of ancient texts, party with local pagans, and explore the horse's mystical power to pull generations and communities together, all in an attempt to discover who built this incredible creature and why.