When he was done, he went and stood at Guantra's side in front of the starboard windows. Outside, sunlight blazed on the quartz-veined cliffs over which the _Varadium_ was passing. Hollow depressions glittered as though filled with sparkling gems, while huge stalagmites lifted jagged edges, shot forth scintillating hues that etched color madness on the dun cliffsides. The sheer cliffs fell away, exposing a massive gap in the mighty mountains. The _Varadium_ poked its dull grey nose downward and sank between the ledges. Staring from the darkened starboard windows, Kortha beheld the iridescent gleam of the mountain-walls turn to yellow and red and green. The colors deepened as the ship lowered on the air currents: grew lavender, then purple. Shadows from the tall cliffsides gave the canyon into which they sank a dark sombreness. "The Blue Grotto is far below the surface," whispered Guantra. "A young lieutenant discovered and told me about it. I checked his findings; had my engineers pay it a visit. Their work resulted in something that will make your eyes shine." With her keel scraping dry red sand, the _Varadium_ edged along the bed of the canyon. Ahead lay a great black orifice in the side of the cliff: a gigantic cave, vast as Mars' mightiest hangar. Even by straining his keen eyes, Kortha could make out nothing beyond that ebon darkness. But when the flier poked its prow into the cave, a battery of tremendous mercury floodlamps leaped to bluish-white life. Blinking in their glare, Kortha looked down at the floor of the cave; found it fitted with great steel cradle, with benches and lathes and tools. The battleflier sank into the cradle with a lurch and a swift righting of its bulk. Springs sighed softly under its weight, cushioning it on a blanket of compressed air. Guantra led Kortha from the stateroom out along the grey deck, toward the gang-plank, saying, "This place has been useful to me. Extremely so. I've found that it paid to spend the money to equip it." Kortha looked around him, gauging his chances for fight. Men stepped to benches, swung down ladders, with an air of deft sureness. They paid him the insult of inattention. His hands knotted, then relaxed. Suppose he did fight? It would do him no good. Even Kortha could not overcome the entire crew of a battleflier. Not without a weapon. Guantra motioned him to a tiny monorail car. "The journey is not far, but we must avoid some--ah--rather terrifying precipices in this. The rail cost fifty lives to install. A misstep above an abyss--" He shrugged, pressing buttons. The car lurched forward, gathered speed. "Personally, I think some of them are bottomless. We could take no soundings." They caught glimpses of black depths to their left as the car slid along on its ribbonlike rail. A string of lights fastened to the cliff cast eerie shadows into the gulf. The car slowed to round a curve.