An ancient shipwreck. A 200-year-old mystery. A plague that's destroying all marine life. A pyramid half a mile below the sea. And a puzzle that must be solved before it destroys the human race.

On the 18th of February, 1812, the Emily Rose became shipwrecked on the southern coast of Australia. The survivors are forced to walk nearly 1,000 miles through the unexplored land to reach the only settlement, Sydney Cove.

Nearly 200 miles inland, they come across the remains of a monstrous ship, far bigger than anything the British Navy had ever constructed. Through basic communication achieved with the natives, they learned that the ship had been there for a very long time...Maybe 1,000 years? Despite the details of the mysterious ship in the journals from the survivors of the Emily Rose, no evidence that the Mahogany Ship ever existed was found - until now.

Present day: A mining exploration in Australia takes a core sample 500 feet below the surface of a deserted mountain. The sample returns no evidence of gold deposits, but something much more valuable - a single Spanish Gold coin, dated 1518. Could the origins of this coin finally reveal the existence of the fabled Mahogany Ship?

At the same time, Sam Reilly and his team of ocean investigators are exploring the cause of a widespread death of sea life within the Gulf of Mexico. In a race against time to stop the irrevocable destruction of the world's marine life, the two mysteries may just be entangled, and failure to solve them both will result in the greatest threat to ever face the human race.