Explore the giant herds that roam the wild grasslands of the plains. Home to the greatest gathering of animal life on the planet, they are also increasingly our bread basket - and among the most endangered places on Earth. Dr. Sanjayan follows a unique elephant conservation project in South Africa and tracks the prairies to see how Americans are saving their most-endangered mammal. His journey uncovers a vital new understanding about how both humans and predators can help the animals found on the plains.