In September of 1940, an 18-year-old mechanic named Marcel Ravidat was walking his dog, Robot, in the countryside of Southwestern France when the dog disappeared down a hole. Robot eventually returned but the next day, Ravidat went to the spot with three friends to explore the hole. And after quite a bit of digging, they discovered a cave with walls covered with paintings, including over 900 paintings of animals, horses, stags, bison and also species that are now extinct, including a wooly rhino...