A group of young boys are out hunting for rabbits near Montignac, France during World War II, when their dog Robot disappears. They hear barking coming from underground and soon discover an overturned tree and a burrow near its roots. The boys dig at the base of the tree to widen the hole, so Ravidat, the oldest of the boys, can lower himself in. When Ravidat realizes the hole leads to an open cave, he calls to the other boys to join him. They rescue Robot and decide to come back the next day with a light source to explore further. Ravidat and another of the older boys, Coencas, return the next day with matches and a grease gun which they use as a light source once in the cave. The boys discover that the cave is much larger than they had anticipated, with several tunnels leading deeper underground. Covering the cave's walls are prehistoric paintings of many different animals, including bison, ponies, and mountain goats. At first, the boys want to keep the secret cave to themselves, but they eventually decide to show their history teacher, who gets in touch with a prehistorian in Paris, Abbé Breuil. Breuil travels to Montignac from Paris, and the boys lead him to the cave. Breuil, who has helped discover similar caves in the past, is amazed at the amount of well-preserved paintings on the cave's many walls. He takes detailed notes and drawings and tells the boys many stories about the other caves he has seen and the history behind them. When Breuil leaves for the day, Ravidat sees Ramón, a mechanic from town, approaching the boys from where he apparently had been lurking nearby. Ramón asks the boys about the cave and tells them that he is part of the _Résistance, _a group of Frenchman who have been secretly preparing for the Germans' arrival in France. Ramón tells the boys that he needs somewhere to store the group's weapons. Though Breuil instructed them not to let anyone see the cave, the boys agree to help Ramón. Over the course of the next few days, Breuil continues to tell the boys stories about his experiences with cave paintings. On one occasion, Breuil was studying a cave when he was approached by a man who was fascinated by the beauty of the drawings. The man was Picasso, but he was not yet famous, and Breuil did not recognize him until years later.