The Earthcore miners, led by Mack Hendricks, are finally ready to explore the caves, but small, unexplained ground tremors threaten lethal danger to anyone who enters. With Angus Kool and Randy Wright, the victims of lab sabotage, can Katarina Hayes find the source of these tremors before it's too late? That’s not her only problem — Hayes is trying to find a reason for an inexplicable miles-long-line that runs across the mountain, and goes down so far they can’t measure the depth. What caused it? What does it mean?