is shoulder,
Gerry saw a rusted iron ring. He tapped on that stone with the hilt of
his sword. He heard a faint click, and though there was no visible
change in the surface of the pitted stone wall before him he heard a
whispered question:

"_Who knocks?_"

"Friends," Gerry replied.

"Who sent you?"

"Sarnak sent us."

There was a low, metallic jingle. A section of the wall about the height
of a man and some three feet wide swung quietly inward. As soon as the
three of them had stepped through the opening into a small room that was
built in the interior of the arch, the door swung shut behind them.

* * * * *

There were half a dozen men in this low roofed and stone walled chamber.
All were of the Green People, dressed as ragged beggars but with the
bearing and appearance of warriors. Drawn steel gleamed in their hands.
Their faces were heavy with suspicion. One of the men had gone to stand
with his back against the closed door behind them.

"Who are you, that come using the name of Sarnak?" snapped the leader.

Suspicion became blended with puzzled surprise as Gerry and Angus threw
back their hoods and the outlaws saw their white skins. Hastily Gerry
told the tale of the dakta hunt and of their subsequent escape.

"So Sarnak got away!" the leader of the Green Men exulted. "Ho! That is
the best news that we of the Dragon's Teeth have heard in many weeks!
All right, Slag, take these strangers through to the inner places."

One of the Green Men beckoned to Gerry to follow him down a narrow
flight of steps at the back of the room. It ended in a circular pool of
water like a large well, the steps going on down below the surface.
Their guide opened a cupboard built into the wall and took out four
glass helmets. The helmets were attached to leather pads that fitted
tightly about the shoulders and chest, with straps to hold them in
place. A cylindrical metal tank was attached to the back of each helmet,
with a tube that led to a valve at the side. The guide also took out
some heavily leaded sandals.

"Put on these helmets and then open the valves," he explained, "then
follow me down the steps. Be careful not to fall in the darkness. After
we get around the first bend in the corridor below there will be light."

Gerry put the globular glass helmet over his head, opening the valve as
soon as he had adjusted the straps. The air in the helmet immediately
took on a faintly chemical odo