In the karst rock forests of North Vietnam, conservationists struggle for the preservation of one of the rarest species of primates in the world: only 250 individuals of the clown-like Tonkin snub-nosed monkeys are left. In 1989, the species believed extinct, was rediscovered. The Sisyphean task of the Vietnamese rangers and biologists in the rough terrain delivered its first successes. As first European journalist, the author accompanied the rangers on a four-day field trip through the remote karst rock mountain region near the Chinese border. He reports on the struggle of conservation of the species, on corruption, poaching and wildlife trade and on the change in the Vietnam of today.