Heartsick, he turned south, and followed the silver stream of the Hudson. The river, lonely as the sky, seemed to drift oily and sluggish down to plunge beneath the city at the lower end of the Tappan Zee. Allan Dane came over New York, gazed down at the ruin of its soaring towers, at the leaping arabesque of its street bridges. He peered into vast rifts of tumbled, chaotic concrete and steel. Nothing moved in all that spreading wonder that had housed twenty millions of people. Allan drifted lower, and saw that from what had been gardened roof-parks, now a welter of strewn earth, the green things had spread till they covered the heaped jetsam with a healing blanket of foliage. Not all the city had been laid waste, however. Here and there, great expanses of the cliff-like structures still stood, undamaged, and in the midst of one of these areas he saw the high-piled edifice to which he had been directed. Its roof was lush with vegetation but by dextrous handling he set his helicopter down upon it. The engine roar diminished and died. Silence folded around him, a black, thick blanket. * * * * * Dane got heavily from his seat, oppressed by the vast soundlessness, and pushed through curling plants that caught at his heels. The sound of his passage was like crackling thunder. A decaying door was marked, in faded, almost undecipherable letters, "Emergency Stairs." It was half open, and Allan squeezed around its edge. Spiral steps curved down into blackness. He hesitated a moment. He could _feel_ the awful silence, the emptiness below was a pit of death. Anthony's words came back to him, echoed in his ears: "We seven are the only living humans left on Earth." In that moment, out of the pitch-black well of soundlessness, a scream shrilled! No words, only a red, thin thread of sound, rising, and falling, and rising again out of depths where not even a living mouse should be! It came again, ripping the silence--a woman's scream, high-pitched, quivering with fear! Allan plunged down into the darkness, caroming from wall to wall as he half ran, half fell, down the twisting stairs. Another sound reverberated from unseen walls, and Dane realized that it was his own voice, shouting. His feet struck level floor. A pale rectangle of light showed before him, and he dived through it. He was in a corridor, dim-lit by phosphorescent fungi that cloaked the damp walls. He halted, at fault. The long hall stretched away to either side, cluttered with grimed bones, slimy with mold. By the age-blistered name cards on closed doors he knew himself to be on a residential level. But which way should he turn? Whence had come that scream? He crouched against the wall, his heartbeats thudding loud in his ears, and listened for a clue.