At the portal David dropped from the step of the engine and made his way, unaccompanied, into the heart of the mountain. The thread of incandescent bulbs starred the blackness, each illuminating its little circle of the underworld. The distant clamor of the drills ceased shortly after David reached the spot where the threatening roof was sprinkling its daily warnings. Posturing solely as the cool-headed engineer and technician, he would have decided at once that the danger signals were growing more portentous--did so decide in the inner depths of him. The overhead rock had an appearance not unlike that of a slaking lime bed, checked and crisscrossed in every direction with fine seams and cracks. While he was still examining the roof and telling himself that this was only one of the many chances that had to be taken in the battle for success, a man came out of the half-lighted darkness of the farther depths and spoke to him. It was Silas Plegg. “Getting your goat so that you can’t sleep nights, is it?” said the first assistant, with his teeth-baring smile. David ignored the reference to his responsibilities and asked a question. “Any more strike talk among the men?” “A little; yes.” “What do you think about this roof by this time? I know what you thought a few days ago.” Plegg shook his head. “It’s not up to me to do the thinking. What do you think?” “Frankly, Plegg, I don’t know what to say. Just before you came up I was thinking that if I were called in here as an outsider and asked to give an opinion I’d say it was a risk--a damned bad risk. But as a Grillage man, I’ve come around to your point of view on the necessities. We’ve got to trust to luck and bully it through.” “Yes; if the devil doesn’t take too good care of his own.” “What do you mean by that?” “I mean that it doesn’t lie with us any more to keep this thing quiet.” “What? Have the inspectors caught on?” “Since we haven’t had a bunch of them jumping onto us, I infer not. But there is at least one warm enemy of yours who knows about it.” “Who is it?” “Black Jack Dargin.” David flew into a rage for the second time that day. “Can’t I get a positive order obeyed any more on this job?” he rasped. “How many times have I got to say that nobody from the outside is to be allowed in this tunnel?” “Dargin hasn’t been here,” said Plegg evenly. “But he has had one of his steerers working here as a mucker.” A pause, and then, in the same even tone: “I guess you’ll have to give up your idea of running Black Jack off the lot. It isn’t worth while, anyway.” David Vallory was still angry. “I’ll be shot if I’ll give it up!” he snapped. “I’ve got a string to pull that will clean those Powder Can dives off the map, and I’ll pull it to-night before I sleep!” “And take the risk of Dargin’s giving this thing away?” “I’m not considering risks just now! If that tin-horn gambler thinks he can put something over on us, let him try it.”