In the latest riveting thriller from the #1 New York Times bestselling author, an international research station in the Coral Sea comes under siege during a geological disaster that triggers massive quakes, deadly tsunamis, and volcanic eruptions. To stop the world from burning, it's up to Sigma Force to uncover a secret buried at the heart of our planet.

The Titan Project--an international research station off the coast of Australia--discovers a thriving zone of life in an otherwise dead sea. The area teems with a strange bioluminescent coral that defies science, yet holds great promise for the future. But the loss of a military submarine in the area triggers a brutal attack and sets in motion a geological disaster that destabilizes an entire region.

Massive quakes, volcanic eruptions, and deadly tsunamis herald a greater cataclysm to come--for something is stirring miles under the ocean, a threat hidden for millennia.

As seas turn toxic and coastlines burn, can Sigma Force stop what has been let loose--especially as an old adversary returns, hunting them and thwarting their every move? For any hope of success, Commander Gray Pierce must search for a key buried in the past, hidden deep in Aboriginal mythology. But what Sigma could uncover is even more frightening--something that will shake the very foundations of humanity.