In a spectacular adventure, NOVA unlocks the mystery on the vast, grassy plains of Kazakhstan, where horses still roam free, and nomadic herders follow their traditional way of life. Investigating clues from archaeology and genetics, researchers reveal vivid evidence of the very first horsemen. They also discover warriors who swept across Europe and turn out to be the ancestors of millions today.

Geologists investigate the forces involved in the formation of the mysterious plateau located 200 miles east of Seattle known as the Channeled Scablands.