A mine's cave in prompts the New England Mining Company to send out two of its best to a small rural Massachusetts town for an investigation. Four man have died and the company needs to know if the mine is safe to bring production back online. The new geologist and structural engineer for the site had given the OK to dig in the location but is baffled that the cave in revealed an enormous cavern previously undiscovered. A structural engineer and a safety inspector for the company are sent to get the facts and determine the safety of the site in hopes that production can continue.