Evoking the excitement of discovery in his illustrations, Litchfield illuminates events both above ground and below with sparkles and broad beams of light. Walking through the woods to get away from the increasingly troubling war news in 1940, young Marcel Ravidat finds some unusual holes—which, as he learns when he returns with three friends to explore, lead to a subterranean wonderland of caves covered in painted animal images. “Arch of a neck,” Pruitt writes in enticing, breathless prose. “Flash of an eye.” “Elk, bison, a Great Black Bull. Horses. So many horses.” The wondering observers, the friends they later let in for a small charge, and then the experts who learned of the discovery asked questions that are still seeking answers: “Who made these paintings? What tools did they use? How did they learn to paint like this?” The illustrator brings the wall creatures to incredibly vivid life: Some make eye contact with visitors; we see shadowy prehistoric artists creating others. The paintings are estimated to be about 20,000 years old, the author explains in a detailed afterword that accompanies photos of select originals and of Marcel and his friends, too. Much about them remains tantalizingly mysterious, though.