Abbey of Ruac, rural France: A medieval script is discovered hidden behind an antique bookcase. Badly damaged, it is sent to Paris for restoration, and there literary historian Hugo Pineau begins to read the startling fourteenth-century text. Within its pages lies a fanciful tale of a painted cave and the secrets it contains and a rudimentary map showing its position close to the abbey. Intrigued, Hugo enlists the help of archaeologist Luc Simard and the two men go exploring.