The outlines of the abyss were changing; the walls breaking down; fire pits opening. For a time--how long I cannot say--we were lost. An hour perhaps? Or more? We flew aimlessly, seeking the tunnel-entrance. Did it still exist? This doomed realm! There were things Tad and I saw in that hour or more of flight which have marked us forever with horror, a myriad small fragmentary glimpses which were all our minds could grasp--tiny fragments of the whole which was beyond conception. The distant red glare spread. We avoided it, flying the other way. Tad thought that the black wall off to our left held the tunnel mouth. But it began breaking, and a wall of water engulfed it. The hot breath of the fires reached us, thickly sulphurous. We soon were gasping. Everywhere the honeycomb was breaking down. Still distant--but the familiar conformations of the abyss were changing. Lost. And then a new hope came to us. The surface beneath us showed clear in the red glare. Houses were here now, and a road. “We’ve passed the tunnel,” Tad shouted. “That’s the road from the Mound--I know the way now!” * * * * * We turned back and followed it. People were down there. Middge and loaded _arras_, running in panic. A muffled explosion sounded through the mingled roar of water and falling rock. A hot sulphurous wave of gas came surging. It seemed to cling to the surface--a black mist rolling, spreading. It engulfed the struggling line of Middge. Its tongues of flame licked at them. They wilted, shriveled. Human cries came up to us--shrill, tiny as shrieking insects. The gas-cloud hid them. “Higher, Tad--we’ll be--choked--” We mounted. The air was pure here, wet with wind and the salt of the inrushing sea. A wall of water came tumbling, engulfing, lashing at the surface, then pounding off to some lower area. A monster--something still alive, struggling with instinct of fear--trumpeted with a strident, uncanny scream. The cry stopped in a moment as the thing was swept away. This doomed realm! “Tad, look! Is that the entrance?” A rock wall still intact loomed ahead of us, and a tunnel mouth, blurred in the mingled spray and smoke. One small beacon light still remained, bleary, winking--vanishing. We landed on the rock with a crash. Unhurt, we jumped from the aëro. Human figures lay here, twisted, huddled shapes. A few still tried to move. We choked with the fumes. I passed a child--dead, clinging in death to its dead mother. A woman alone--gruesomely burned from some flaming tongue which had licked the rocks here. I stooped. No, it was not Nereid. We thought we had come to the niche where Arturo and Nereid were to meet us. It was empty. We stumbled away. In the tunnel mouth the air seemed momentarily better. A man struggled ahead of us, then fell, lay still. I stooped over him. No, not Arturo.