They stood high on the side of the Ryzga mountain, and gazed at the doorway. It was an opaque yet penetrable well of darkness, opening into the face of a lava cliff, closed only by an intangible curtain--so little had the Ryzgas feared those who might assail them in their sleep. Var sent his thoughts probing beyond the curtain, listened intently, head thrown back, to their echoes that returned. The tunnel beyond slanted steeply downward. Var's hands moved, molding a radiant globe from the feeble sunshine that straggled through the fog-bank. With an abrupt motion he hurled it. The sun-globe vanished, as if the darkness had drunk it up, but though sight did not serve they both sensed that it had passed through to light up the depths beyond. For within the mountain something snapped suddenly alert--something alive yet not living, seeing yet blind. They felt light-sensitive cells tingle in response, felt electric currents sting along buried, long-idle circuits.... The two stood shivering together. The morning wind stirred, freshening, the fog lifted a little, and they heard a great voice crying, "There they are!" Var and Neena turned. Far out in the sea of fog, on a dream bridge that they could not see, stood Groz. He shook the staff he carried. It was too far to discern the rage that must contort his features, but the thought he hurled at them was a soundless bellow: "Young fools! I've caught you now!" Behind Groz the figures of his followers loomed up as striding shadows. Neena's hand tightened on Var's. Var sent a thought of defiance: "Go back! Or you'll drive us to enter the mountain!" Groz seemed to hesitate. Then he swung his staff up like a weapon, and for the two on the mountainside the world turned upside down, the mountain's black shoulder hung inverted above them and the dizzy gulf of sky was beneath. Var fought for footing with his balance gone, feeling Neena reel against him until, summoning all his strength, he broke the grip of the illusion and the world seemed to right itself. The mist billowed again and Groz was out of sight, but they could hear him exhorting his men to haste. Neena's face was deadly pale and her lips trembled, but her urgent whisper said, "Come on!" Together they plunged into the curtain of darkness. * * * * * At Var's thought command Neena froze instantly. "Feel that!" he muttered, and she, listening, sensed it too: the infinitesimal trickle of currents behind what appeared to be a blank tunnel wall, a rising potential that seemed to whisper _Ready ... ready.... _ The sun-globe floated behind them, casting light before them down the featureless tunnel that sloped always toward the mountain's heart. Var summoned it, and it drifted ahead, a dozen feet, a little more-- Between wall and wall a blinding spindle of flame sprang into being, pulsed briefly with radiant energy that pained the eyes, and went out. The immaterial globe of light danced on before them.