Naturalist Joe Hutto’s latest adventures in wildlife observation take him to Wyoming’s Wind River Mountains. Hutto is living in a tent at 12,000 feet, where blizzards occur in July and where human wants become irrelevant and human needs can become a matter of life and death—to study the Rocky Mountain bighorn sheep. The population of these rare alpine sheep is in decline. The lambs are dying in unprecedented numbers. Hutto’s job is to find out why. For months at a time, he follows the bighorn herds, meets mountain lions and bears, weathers injury and storms, and beautifully observes the incredible splendor of the Rocky Mountains. Hutto has a deep connection to Wyoming, having managed a large cattle ranch in his past. He weaves Wyoming’s history of the cowboy, mountain ecology, and the lives of the bighorn sheep into a beautiful flowing narrative. Ultimately, he discovers that the lambs are dying of a form of nutritional muscular dystrophy due to selenium deficiency, which is caused by acid rain—a grim ecological disaster caused by human pollution. Here is a new twist on a cautionary tale, and a new voice, eloquently ex-pressing the urgency that we mend our ways.