Sonny McGuiness and Cho Takachi have been researching the history of the Wah Wah mountains and the Silver Spring, the find that put Earthcore on the hunt for the biggest platinum deposit ever discovered. They have found a disturbing artifact, a deadly artifact, and must learn more. Meanwhile, Connell Kirkland must find a mining engineer that can dig to a world-record depth of three miles underground. Mack Hendricks is that engineer — can Connell convince him to join the project? And all this time, disgraced NSA agent Kayla Meyers has been digging for a different kind of treasure — the secret of the hidden mine’s location, and how she can turn that into a new life for herself.