Speed mounted. Colliding with anything in that tunnel would have brought the men unknowing death. But now the throttle was limp and unresponsive. So what was there to do but rely anxiously on probable automatic guiding devices? In minutes the car covered four thousand miles, and then stopped by itself with a soft, innocuous jolt. Finden undogged the portal of the projectile by working levers not made for human hands. Again the glowing walls gave light. Boots made grating sounds. So there was air, too. Gaseous, not frozen. Again they wandered through passages and rooms. Here was a great underground fortress and supply depot. Metal crates and boxes were stacked high. There were hugely buttressed walls, some of them ruptured and repaired. Martian and Xian corpses, relics of a last battle, lay dried out and blackened on the floor. At last the men came to a long vaulted hall. Near them was the breech of a colossal tube, ten yards in diameter. Beyond it was another and another, a whole bank of them, fifty in a row, slanting slightly upward and disappearing into the metal wall. * * * * * The men sensed it at once--in this colossal setup must be what they had come to see. Here was the mysterious center of things. They might have spoken of this aloud. But in this age-old place they were warned to silence. And it wasn't all intuition and wariness. For along the center of that hall, the dust was almost obliterated by human bootprints. Stepping very lightly, Rick and his companions hid behind a metal column where a mummified Martian sprawled on the pavement amid heaps of parchment. Nearby was an Xian corpse. Then they heard a voice. A whisper, almost. It came to their ears directly as sound, penetrating easily the insulating texture of their oxygen helmets: "Give back a world.... Me...." It was a man's gloating mutter to himself. A vain man's promise to his ego, which the frustrations and competition of life had made swollen, like a cancer. Then they saw his blurred shadow on the wall. Thin, hunched over, working at something. Fane all right. He had arrived here ahead of them, by rocket vehicle. No chance could be taken, questioning him. That could be done when and if he was overpowered. Rick Mills raced around the column and leaped. But the scrape of his space-boots was a small warning. Fane was almost able to meet him with the muzzle of a blaster. But Rick, hurtling into him with his shoulder, grabbed his wrist, and the weapon skittered across the floor. Yet though his face-window was open, Fane wore a space armor, too. It protected him from the onslaught. Besides, he was not near exhaustion. And his thin muscles were like wire cables. Moreover, he fought as if for all he had ever hoped for. Some terrific prize. He was like a silent maniac. Even so, Rick almost pinned him down. Lattimer recovered the blaster. Finden was leaping. But Fane touched controls on a square box at his belt. A strange old box.