"In the mountains of Croatia, an archaeologist makes a strange discovery: a subterranean Catholic chapel that holds the bones of a Neanderthal woman. In the same cavern system, elaborate paintings tell the story of a battle between tribes of Neanderthals and monstrous shadowy figures. Who is the mysterious enemy depicted in these ancient drawings and what do the paintings mean?
Before any questions can be answered, the investigative team is attacked, while at the same time, a bloody assault is made upon a primate research center outside of Atlanta. How are these events connected? Who is behind these attacks?
With our future at stake, Commander Gray Pierce and Sigma Force embark on their most harrowing quest ever - from ancient tunnels in Ecuador to a millenia-old necropolis. Gray Pierce and his team will face their greatest threat: an ancient evil, resurrected by modern genetic science, strong enough to bring about the end of man's dominance on this planet.
Only this time, Sigma will falter - and the world we know will change forever." --Provided by publisher.

Adult

Text in English