Keeping the craft low, for the buoyancy tanks were still intact, the girl skimmed the ground until the gently-moving wind had carried her to the side of the last hill that intervened between her and the structure she had thought a man-built tower.  Here she brought the flier to the ground among some stunted trees, and dragging it beneath one where it might be somewhat hidden from craft passing above, she made it fast and set forth to reconnoiter.  Like most women of her class she was armed only with a single slender blade, so that in such an emergency as now confronted her she must depend almost solely upon her cleverness in remaining undiscovered by enemies.  With utmost caution she crept warily toward the crest of the hill, taking advantage of every natural screen that the landscape afforded to conceal her approach from possible observers ahead, while momentarily she cast quick glances rearward lest she be taken by surprise from that quarter.

She came at last to the summit, where, from the concealment of a low bush, she could see what lay beyond.  Beneath her spread a beautiful valley surrounded by low hills.  Dotting it were numerous circular towers, dome-capped, and surrounding each tower was a stone wall enclosing several acres of ground.  The valley appeared to be in a high state of cultivation.  Upon the opposite side of the hill and just beneath her was a tower and enclosure.  It was the roof of the former that had first attracted her attention.  In all respects it seemed identical in construction with those further out in the valley—­a high, plastered wall of massive construction surrounding a similarly constructed tower, upon whose gray surface was painted in vivid colors a strange device.  The towers were about forty sofads in diameter, approximately forty earth-feet, and sixty in height to the base of the dome.  To an Earth man they would have immediately suggested the silos in which dairy farmers store ensilage for their herds; but closer scrutiny, revealing an occasional embrasured opening together with the strange construction of the domes, would have altered such a conclusion.  Tara of Helium saw that the domes seemed to be faced with innumerable prisms of glass, those that were exposed to the declining sun scintillating so gorgeously as to remind her suddenly of the magnificent trappings of Gahan of Gathol.  As she thought of the man she shook her head angrily, and moved cautiously forward a foot or two that she might get a less obstructed view of the nearer tower and its enclosure.

As Tara of Helium looked down into the enclosure surrounding the nearest tower, her brows contracted momentarily in frowning surprise, and then her eyes went wide in an expression of incredulity tinged with horror, for what she saw was a score or two of human bodies—­naked and headless.  For a long moment she watched, breathless; unable to believe the evidence of her own eyes—­that these grewsome things moved and had life!  She saw them crawling about on hands