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.

Supplemental enhancement PDF accompanies the audiobook.