"We'd better not stay down in this maze of pipes too long,” warned Sual Av. “The rains will start again when dawn comes, and these tubes will be full of rushing water."
John Thorn was clambering into the smaller side drain. It was so small that he had to go forward in it on hands and knees. It sloped very gently upward, and its floor was damp.
He led the way, the little red beam of his fluoric lamp lighting him forward. Sual Av followed him closely, and the big Mercurian brought up the rear.
Thorn guessed that by now they must be passing under the wall of the great fortress. His hopes were running high. So far, they had met no barrier.
Then suddenly, Thorn met the barrier. And he almost died before he realized it.
The little tubular fluoric lamp he held outstretched in front of him suddenly flared red hot, its chromaloy case starting instantly to melt. Thorn recoiled with a smothered exclamation of pain and surprise, dropping the redhot thing. They were plunged into absolute darkness,
"What is it?” exclaimed Sual Av anxiously.
"I don't know. Something ahead melted my lamp before I could draw back,” Thorn answered, his voice wiretaut in the darkness. “Pass me your lamp, Sual. We've run into some devilish trap!"
The Venusian passed his lamp forward. Thorn, without venturing any farther forward, snicked on the beam.
The red ray quivered up the gently sloping black cement tube. Thorn stared tensely. There was nothing ahead — nothing except a row of small holes across the curved floor of the drain, and a similar row of holes in the roof exactly above.