When the books are sent to Paris for restoration after a fire at an ancient church in the village of Ruac in the Black Perigord region of France, Hugo Pineau, an expert in medieval manuscripts, discovers the enigmatic script with 14th-century text. It contains a fanciful tale of a painted cave and its secrets. Included is a rudimentary map showing the position of the cave along the Vezere River. Along with archaeologist Luc Simard and Sara Graham, a visiting professor at the University of Paris, they begin a dangerous journey and soon find themselves at the centre of a dangerous game as people within their inner circles are killed off - one by one...