The caves of Prigord - Martin Walker

The darkest chapter in the history of the French Resistance was written in blood, in a cave in Perigord half a century ago.
When British Army officer Major Philip Manners brings a piece of stone art to a London auction house, he stuns the archaeological world. The relic is a fragment of a stone painting 17,000 years old, kept secret by Manners' father since his service in France during the Second World War. To archaeologists, it may be the key to a site even more important than Lascaux. To others, it represents a secret believed to be safely buried. News of its discovery recalls haunting memories and the bitter taste of fear.
No matter the methods, no matter the cost, the truth must remain interred. For the world must never know what happened more than fifty years ago in occupied France, in the Caves of Perigord...