d the open door and window. He pressed another button, and
sheeted lead curtains rolled swiftly over the vita-crystal roof,
darkening the room, cutting off the rays of diffused sunlight. Then he
seated himself not far from the captives, facing them, grinning
savagely. Hilary wondered why.

Again what seemed hours passed. Behind the lead curtain, the room had
become definitely, uncomfortably warm. The Earthlings perspired; the
atmosphere was literally steaming; and in their cramped limbs, the
torture was fast becoming unbearable. Only the Mercutian guard did not
seem to mind. He was accustomed to far higher temperatures on the arid
planet that was his home.

Just as the prisoners were gasping almost their last gasp, the heat
seemed to recede, swiftly. At once the guard rolled back the leaden
shade opened the door and window again. His grin was broadly
triumphant. Something clutched at Hilary's heart; he understood now.
The beastly invaders! He struggled furiously at his bonds, but they
did not give. He ceased his efforts, panting.

The moments passed. Hilary was giving up whatever slender hopes he had
had. Wat and Grim had not heard, or if they did, they could do
nothing. A slow, sullen despair enveloped him.

He was watching the guard. That gray-faced giant turned his head
suddenly, jumped up as fast as his lumbering alien weight could move,
snatched at his sun-tube.

"Don't move an inch, if you want to live," a deep, slow voice vibrated
through the room. A well-remembered voice. Hilary would have laughed
aloud his relief, but he was gagged. His comrades had not failed them.

* * * * *

The guard dropped his half-raised weapon sullenly, staring at the
intruders in dazed incomprehension. Hilary jerked his head around.
Framed in the doorway was Grim--good old Grim--a long-barreled dynol
pistol steady in his hand. From behind him there darted a little
figure, red-haired, freckled, shrill with delight. An old-fashioned
submachine gun, abstracted from some museum, weighed heavily under his
arm.

It clattered unheeded to the floor as the bantam dived for Hilary and
Joan.

"We came as fast as we could when we got your message," he crowed.
"Dropped everything." His nimble fingers were making havoc of the
knotted bonds, while his nimbler tongue wagged on. "Boy, we have them
on the run. We'll sweep them out into space by the time we're
through."

Hilary and Joan were free now. Very pai