Lynn screamed and tugged at the door beside her. In a moment more she would have been carried out across the deadly sands without a shield of any sort. But just as the roller left the road, the girl threw herself through the door ... fell sprawling on the edge of the roadbed. The roller bounced out fifty ... a hundred ... two hundred yards into the desert-land ... then stalled. It lay there, a dark form dimly outlined against the thin iridescence of the soil, a silent vehicle bearing a single, unconscious occupant. Lynn Graham stared at it dolefully for a few moments. Then, because there was no use crying over spilt milk--or lost means of transportation--she turned and hurried toward the city as quickly as possible ... afoot. * * * * * As they approached the hill in the darkness, the two S.I.D. men were aware of much activity going on around them. They heard the cries of foremen, the grunts of laborers, the chuff-chuff of old-fashioned combustion engines, and the high, shrill whining of a single highpowered atomotor. Rocky glanced at the New Boston factor inquisitively. "Mining, Grossman--already?" Grossman chuckled. "Mining, yes. But not for what you think. Before we mine for wealth, we must mine for power." "Mine for power?" "You shall see in a moment what I mean." Grossman motioned one of his native aides to him. "Ho, there! He is secure? The mighty one is shackled as I commanded?" "Yes, O Master. He is bound wrist and ankle." "Good! And the excavation?" "Proceeds on schedule, Master. By dawn it should be finished." "That is well. For if he still grows--" "He does, O Master!" "--dawn will be none too soon. The cavern will no longer hold him." Bud whispered to his friend and superior, "Say, what goes on here? What are they talking about?" "If I'm not greatly mistaken," answered Rocky, "the thing for which those manacles were made." Verification of his guess came almost immediately. Again their guards prodded them forward, and behind Grossman they entered a passageway dipping into the side of the hill. Through an ancient tunnel, damp and malodorous, they marched, debouching finally into a gigantic cavern ... a huge bubble of emptiness blown into the solid rock in some forgotten geologic age of change. And there at last before them stood.... No ... it did not stand. There was no longer room for it to stand upright in an underground cavern whose roof was but three hundred feet high. It crouched. It knelt upon all fours like a great, mute beast; knelt and stared with dumbly questioning eyes at the tiny motes now entering its lair to look upon it. It had been secured, as the Titanian had said, with great metal manacles, from the welded joints of which stretched mighty chains so huge that a man might walk upright through a single loop. Its wrists were also gyved, and a length of chain swung between the two.