 Up to 1/3 of the North American continent was covered with grass as late as 150 years ago, but today the tallgrass prairie is the most endangered ecosystem in North America - less than 5% is left standing in the Flint Hills of Kansas and the Osage Hills of Oklahoma. Most of the bread, cereals, and beef we eat is produced by current and former grasslands. Grasslands also purify the air we breathe, removing carbon from the air and supplying oxygen. This documentary looks at the history, present, and future of the central North American grasslands, from its beginnings after the last Ice Age to the culture of the Plains Indians and the settlement by white Europeans, who plowed under the grass and planted row crops. The relationships between the grass, grazing animals such as buffalo and cattle, fire, and humans is key to the future of the grasslands.