They had not long to wait. A group of human beings--men and to all appearance Americans--appeared unarmed in the little lounge. As soon as they were well inside the room, Bradley and Costigan released upon them without compunction the full power of their frightful projectors. From the reflectors, through the doorway, there tore a concentrated double beam of pure destruction--but that beam did not reach its goal. Yards from the men it met a screen of impenetrable density. Instantly the gunners pressed their triggers and a stream of high-explosive shells issued from the roaring weapons. But shells, also, were futile. They struck the shield and vanished--vanished without exploding and without leaving a trace to show that they had ever existed. Costigan sprang to his feet, but before he could launch his intended attack a vast tunnel appeared beside him--an annihilating ray had swept through the entire width of the liner, cutting instantly a smooth cylinder of emptiness. Air rushed in to fill the vacuum, and the three visitors felt themselves seized by invisible forces and drawn into the tunnel. Through it they floated, up to and over the buildings, finally slanting downward toward the door of a great high-powered structure. Doors opened before them and closed behind them, until at last they stood upright in a room which was evidently the office of a busy executive. They faced a desk which, in addition to the usual equipment of the business man, carried a bewilderingly complete switchboard and instrument panel. Seated impassively at the desk there was a gray man. Not only was he dressed entirely in gray, but his heavy hair was gray, his eyes were gray, and even his tanned skin seemed to give the impression of grayness in disguise. His overwhelming personality radiated an aura of grayness--not the gentle gray of the dove, but the resistless, driving gray of the super-dreadnaught; the hard, inflexible, brittle gray of the fracture of high-carbon steel. "Captain Bradley, First Officer Costigan, Miss Marsden," the man spoke quietly, but crisply. "I had not intended you two men to live so long. That is a detail, however, which we will pass by for the moment. You may remove your suits." Neither officer moved, but both stared back at the speaker unflinchingly. "I am not accustomed to repeating instructions," the man at the desk continued; voice still low and level, but instinct with deadly menace. "You may choose between removing those suits and dying in them, here and now."