The northern white rhino teeters on the brink of extinction. At Ol Pejeta Conservancy and the San Diego Zoo’s Frozen Zoo, scientists, vets, and caregivers like Zach Mutai, Marlys Houck, and Dr. Florence Kang’ethe are racing against time to bring the species back. Through groundbreaking science and deep compassion, they’re writing a hopeful final chapter — before the book closes for good.