Twice thought to be extinct, black-footed ferrets are now the most endangered native mammal in the United States. A top predator species of the Western plains, black-footed ferrets eat prairie dogs almost exclusively. Since the late 1800s, however, 98 percent of the prairie dog population has been exterminated by ranchers, farmers and others who consider the animals pests. The last 18 wild ferrets were captured in Wyoming in 1981 in an attempt to save the species. Seven of those ferrets were bred successfully in captivity; all 800 or so ferrets alive today are their descendants. These captive-bred ferrets are released into the wild in areas with some of the last remaining large prairie dog populations. But sylvatic plague, brought to the New World around 1900, continues to wipe out wild ferrets and prairie dogs. And the continuing loss of grassland habitat, along with new threats like Covid-19, make the animals’ comeback even more tenuous. As this life-and-death saga continues to unfold across the open plains of the American West, this book documents what it takes to bring an animal back from the brink of extinction.