They came to a
stop--paused, weightless--a vast door slid smoothly aside--they were
drawn _upward_ through an airlock and floated quietly in the air above a
small, but brightly-lighted and orderly city of metallic buildings!
Gently the _Hyperion_ was lowered, to come to rest in the embracing arms
of a regulation landing cradle.

"Well, wherever it is, we're here," remarked Captain Bradley, grimly.

"And now the fireworks start," assented Costigan, with a questioning
glance at the girl.

"Don't mind me," she answered his unspoken question. "I don't believe in
surrendering, either."

"Right," and both men squatted down behind the ether-walls of their
terrific weapons; the girl prone behind them.

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 di