Hidden in the gorges of Southern France lies one of the most stunning decorated caves ever discovered: Chauvet, 'the Sistine Chapel of Paleolithic art.' For thousands of years, this geological wonder was visited only by animals. But around 37,000 years ago people arrived, and some covered its walls with drawings of exceptional beauty. Since its re-discovery in 1994, only a few scientists have been granted access to study it. Now, NOVA's cameras are there as scientists return to the cave searching for new clues about the people who came here - and what moved them to leave such haunting images.