The Planeteers are climbing Mount Everest in the Himalayas when they follow a snow leopard and fall into a cavern where they encounter a Yetti among 12 extinct or endangered animals, all of whom can speak, and begin to judge not only the Planeteers, but the entire human race. They go back from the Ice Age and various other time periods where the animals were either hunted or had their habitats destroyed by humans resulting in their extinction or becoming endangered.