Using a hand hoe and working in dim light, geologist Otto Völzing burrowed into the earth deep inside the Stadel cave in the Schwäbische Alb mountains of southwestern Germany. His finds were interesting to be sure, but nothing world-shaking: flints and the remnants of food eaten by prehistoric human beings.

Suddenly he struck a hard object -- and splintered a small statuette.

It was 1939 and Völzing didn't have much time. He had just been called up to serve in the military and World War II was about to begin. He quickly packed the pieces into a box and the excavation, which was being financed by the SS, was terminated on the same day....