She was the first to study gorillas in their natural environment: the high mountains of Rwanda, where she settled in 1967. For nearly twenty years, Dian Fossey lived with the gorillas, observed their behavior, and changed the way people viewed them. Her relentless fight against poaching prevented the species from becoming extinct. But in December 1985, the primatologist was murdered, and the mystery surrounding her death remains unsolved. Former colleagues, scientists, and biographers shed light on the impact of her work, but also on the darker sides of her personality and her uncompromising commitment.