From the black, night-wrapped valley, far below, the singer's voice went silent with the slamming of a door in one of the bunkhouses. The song was popular; some rimester in the Tonah Basin camp had written the parody for the tormenting of the drill crews. And, high on the mountainside, Dean Rawson hummed a few bars of the lilting air after the singer's voice had ceased. "Ten miles down!" he said at last to his assistant, sprawled out on the stone beside him. "That's about right, Smithy. And maybe the rest of the doggerel isn't so far off either. 'Pokin' through the crust of hell'--well, there was hell popping around here once, and I am gambling that the furnaces aren't all out." They were on the outthrust shoulder of rock where the mountain road hung high above the valley floor. Below, where, months before, Rawson had rescued a man from desert death, was blackness punctured by points of light--bunkhouse windows, the drilling-floor lights at the foot of a big derrick, a single warning light at the derrick's top. But the buildings and the towering steelwork of the derrick that handled the rotary drills were dim and ghostly in the light of the stars. "We've gone through some places I'd call plenty warm," said Smithy, "but you--you craves it _hot_! Think we're about due?" he asked. Rawson answered indirectly. "One great big old he-crater!" he said. His outstretched arm swept the whole circle of starlit mountains that enclosed the Basin. "That's what this was once. Twenty miles across--and when it blew its head off it must have sprayed this whole Southwest. "Now, those craters"--he pointed contemptuously toward the three conical peaks off to the right--"those were just blow-holes on the side of this big one." * * * * * In the ragged ring of mountains, the throat of some volcanic monster of an earlier age, the three cones towered hugely. Their tops were plainly cupped; their ashy sloping sides swept down to the desert floor. At their base, the gray walls of stone in the ghost town of Little Rhyolite gleamed palely, like skeleton remains. "I've seen steam, live steam," Rawson went on, "coming out of a fissure in the rocks. I know there's heat and plenty of it down below. We're about due to hit it. The boys are pulling the drill now; they cut through into a whale of a cave down below there--" He broke off abruptly to fix his attention on the dark valley below, where lights were moving. One white slash of brilliance cut across the dark ground; another, then a cluster of flood lights blazed out. They picked the skeleton framework of the giant derrick in black relief against the white glare of the sand. From far below; through the quiet air, came sounds of excited shouting; the voices of men were raised in sudden clamor. "They've pulled the drill," said Rawson. "But why all the excitement?"