In 1940, four teenage boys and a dog dropped themselves into a hole in the forest floor. Using a flaming grease gun as a torch, they ventured deep underground, eventually coming to a huge cave, the walls of which were covered with life-size paintings of animals. Whole herds of horses! Deer with horns as big as tree branches! Giant bison! The boys were amazed by their discovery. They'd stumbled upon the world's finest examples of prehistoric painting!