Once they stopped short and slender rods reached out and touched, and the sledge slid delicately over them and was itself a bridge across a crevasse in the ice that went down unguessably. Then it went on and the rods were retrieved. Minutes later the sledge-motor was roaring loudly, but it barely crawled up to what appeared to be a mountain crest--there were ranges of mountains extending beyond seeing in the weird blue-and-golden skylight--and then there was a breathtaking dash and a plunge into what was incredibly a natural tunnel beside the course of an ice-river--and abruptly there was a vast valley below. This was their destination. Some thousands of feet down in the very valley-bottom there was a strange, two-mile-long patch of darkness. The blue-gold light showed no color there, but it was actually an artificially warmed pastureland like that within and about the landing grid. But from this dark patch vapors ascended, and rolled, and gathered to form a misty roof--which was swept away and torn to tatters by an unseen wind. The sledge slowed and stopped beside a precipitous upcrop of stone while still high above the valley bottom. A voice called sharply: "It's us," growled Hunt's deep voice. "We got him. Everything all right?" ... "No!" rasped the invisible voice. "They broke out--he broke out and got her loose, and they run off again. We shoulda killed 'em and had done with it!" Everything stopped. The men on the sledge seemed to become still in the shock of pure disaster, pure frustration. Calhoun waited. Hunt was motionless. Then one of the men on the sledge spat elaborately. Then another stirred. "Had your work for nothing," rasped the voice from the shadow. "The trouble that's started goes for nothing, too!" Calhoun asked crisply: "What's this? My special patients ran away?" "That the Med man we heard about?" The invisible speaker was almost derisive with anger. "Sure! They've run off, all right! Man and girl together. After we made trouble with Three City by not killin' 'em and One City by sneakin' over to get you! Three City men'll come boiling over--" The voice raised in pitch, expressing scorn and fury. "Because they fell in love! We shoulda killed 'em right off or let 'em die in the snow like they wanted in the first place!" * * * * *