The mysterious disappearance of chief engineer Jonathan Finch, interrupts the construction of a trunk railway. The construction company is forced to freeze works. The head of the company sends film footage with records of the accident to his friend, an ex-army officer called Richard Stone. Richard's attention rivets one of the tragical moments. He notices a stone monument, and its origin becomes a riddle for the hero. Having agreed to participate in the investigation, Richard doesn't suspect that he's on a dangerous path as a defender of an ancient civilization.