Enter a world of tender friendships, staunch loyalties, violent jealousies--and enduring love.

As a child, Sheri Speede knew that she wanted to advocate for animals in any way she could. But it was not until many years after veterinary school, when she was transporting a chimpanzee named Pierre away from a biomedical facility as part of her job as a conservation advocate in Cameroon, that Dr. Speede discovered her true calling. She began to search for land for a forest sanctuary for captive chimpanzees that were held on chains and in small cages at local hotels.

Dr. Speede...