Ten-year-old Brandon Fletcher and his family are on holiday in France. When visiting prehistoric caves, they experience the marvels of Neanderthal wall paintings.Among the images of extinct animals are strange little symbols, including an especially baffling one called the Phantom Face. Brandon meets Luke, a French boy with a family secret. When hunting for fossils, the two new friends find something both strange and exciting. The discovery sheds light on Luke's mysterious past- and takes Brandon one step closer to figuring out the real meaning of the Phantom Face!