Coming!"

Friday was bringing up the rear as fast as he could. He came sideways in
a zigzag course ducking and whirling constantly, and in between firing
promptly at any portions of enemy anatomies that dared project into the
line of the corridor. The Hawk covered the last few yards of his
retreat, and then they were together at the laboratory.

"The knob!" Carse ordered, spraying the corridor in general warning.

Friday tried it, but the door was locked. He hurled himself against it,
but it did not budge.

How to get through? On the other side of the door was Leithgow, and
probably Ku Sui; on this side they were trapped in a blind end. They
could never make it back down that gauntlet and live, and anything like
concerted action on the part of the yellows would do for them where they
were.

That concerted action came at once. Seventy feet behind, a heavy
shot-projector was pushed out on its little rollers from one of the
doors. A hand reached out and whirled it so that its muzzle bore
straight down the corridor at them. Carse shot at the hand, but the
target was too small even for his fine eye, and he missed; Friday
silenced an emboldened orange spot of light that was spitting streaks at
them.

Hopeless! It looked like the end. Hawk Carse's face was in its old,
emotionless mold as he waited, his gun sharp on the spot where the hand
must reappear if they would fire the deadly projector. He had to get
that hand--and any others that took its place. An almost impossible
shot. He couldn't rush it and get it too. Not in time.

A moment passed. The hand flashed out; Carse shot and again missed. Then
a narrow cone was along the corridor, a blinding orange streak.
Instantly, with a rasp of thunder, it was gone, and the air was
stifling.

The Hawk was untouched; Friday, too, he saw. The bolt had been taken by
the door--and one of the door's two halves was ajar!

* * * * *

At once Hawk Carse acted. "Inside!" he yelled, then was through, the
negro right behind. Carse's eyes swept the laboratory. It was a place of
shadows, the sole light being a faint gleam from a tiny bulb-tipped
surgical tool which glimmered weirdly from the bank of instruments
waiting by the operating table. Carse saw no one.

"Hold the door!" he ordered. "I don't think it'll lock!"

Friday obeyed. He found the inner bolt melted and the lock inoperative;
and, placing his forearms on either side of the middl