They only laughed derisively, with howls of demoniacal scorn.
"You slave! You cur!" shouted Waldron, and spat at him as he drew the vault door shut. "You cringing dog—stay there, now, and face it!"
The great door boomed shut. In the cool of the winding stairway of steel which led, lighted by electricity, to the trap-door and the ladder down into the tremendous vaults, the world-masters breathed deeply once more, respited from death.
Herzog, screaming like a fiend in torment, clawed at the impenetrable steel door, raved, begged, entreated, and tore his fingers on the lock.
No answer, save the muffled echo of a jeer, from within.
Boom!
Mad with terror though he was, he whirled about, and faced the room now quivering with heat.
Even as he looked, a great gap yawned in the western wall, farthest from the flame-belching oxygen-tank that had been struck.
Through this gap, pouring irresistibly as the sea, swept a tide of attackers, storming the inner citadel of the infernal, world-strangling Air Trust.