"That's fine,” rasped Gunner angrily. “Now all we have to do is to go back out in the city, order a nice set of inertrum plugs, and come back here with them. The secret police out there wouldn't think of bothering us while we're doing all that."
"Shut up, Gunner,” Thorn said. “I've an idea which might work."
He fumbled in the pouch that was still attached to his belt. Out of it, he drew the gleaming white slith teeth they had taken from the monsters they had slain in the fungus forest. There were a dozen of the teeth, long, conical fangs an inch across at the root.
"These slith teeth might do the trick,” Thorn muttered. “They're one of the hardest and most perdurable substances in the system, remember — almost as hard as inertrum. If we plugged the heat-beam apertures with these—"
"They couldn't last more than a few seconds before the beams burned them out!” Sual Av exclaimed.
"A few seconds ought to be enough for us to get past,” Thorn retorted. He hesitated, then added, “The last man will run the most danger. We'll back down to the main drain, and I'll, take the rear position."
"You'll not!” Gunner Welk declared. “Hell's name, do you want to play around in these slimy pipes all night? Go ahead and put the teeth in those holes, and let's got on — if it works,"
"All right,” Thorn said grimly. “When I give the word, jump after me as fast as you can, and don't knock any of the teeth out of the holes!"
Thorn rapidly prepared for their precarious stratagem. There were six holes around the perimeter of the drain from which the deadly, invisible beams emerged. He took the six most regularly-shaped of his slith-teeth, and laid them in readiness.
Then with the end of his lamp, Thorn swiftly pushed the teeth into place. As each big white tooth was shoved forward, it became a conical plug to close the beam-aperture. By the time the sixth tooth was tamped into place, the first one was already charring and smelling.