The floor of the tunnel looked as though something very heavy had been dragged along it. At the far end was what had once been a large metal door, but which now consisted chiefly of curled strips around a huge hole. Before it was a small, blackened lump which might once have been a man.
Vanderberg recoiled. " Look, at that!" Then he hurried toward the ruined door. McCoy knelt quickly beside the charred lump, tricorder out; Kirk and Spock followed Vanderberg.
Inside, the bulk of the reactor was buried in the walls, showing only a large faceplate and a control panel. Pipes crisscrossed the chamber; and an appalled Vanderberg was standing looking down at a sort of nexus of these—a junction that ending in nothing.
Kirk scanned the control panel. "I didn't know anyone still used fission for power."
"I don't suppose anybody does but us. But pergium is money—we ship it all out—and since we have so much uranium nobody wants, we use it here. Or we did until now."
"Explain."
"The main moderator pump's gone. Lucky the cutouts worked, or this whole place would be a flaming mass of sodium."
Spock knelt and inspected the aborted junctions. "Acid again. Like the door. Mr. Vanderberg, do you have a replacement for the missing pump?"
"I doubt it. It was platinum, corrosion-proof, never gave us any trouble; should have lasted forever." Suddenly, visibly, Vanderberg began to panic. "Look, the reactor's shut down now—and it provides heat and electricity and life support for the whole colony! And if we override, we'll have a maximum accident that will poison half the planet!"
"Steady," Kirk said. "Mr. Spock, might we have a replacement on shipboard?"
"No, Captain. To find one, you would need a museum."
Kirk took out his communicator. "Kirk to Enterprise . . . Lt. Uhura, get me Mr. Scott . . . Scotty, this is the Captain. Could you contrive a perfusion pump for a PXK fission reactor?"
"Hoo, Captain, you must be haverin'."
"I'm dead serious; it's vital."
"Well, sir—I could put together some odds and ends. But they wouldn't hold for long."
"How long?"
"Forty-eight hours, maybe, with a bit of luck. It all ought to be platinum, ye see, and I've not got enough, so I'll have to patch in with gold, which won't bear the pressure long . . ."
"Get together what you need and beam down here with it."
Kirk put away the communicator and bent upon Vanderberg a look of deep suspicion. "Mr. Vanderberg, I have to tell you that I don't like the way these coincidences are mounting up. How could some hypothetical monster attack precisely the one mechanism in an almost ancient reactor which would create a double crisis like this? And how would it happen to be carrying around with it a mixture of acids precisely calculated to dissolve even platinum—and also human flesh?"
"I don't know," Vanderberg said helplessly. "You suspect sabotage? Impossible. Besides, Ed Appel saw the monster."
"He says."
"Ed's been my production chief almost throughout my entire career. I'd trust him with my life. And besides, what would be his motive? Look, dammit, Kirk, my people are being murdered! This is no time for fantasies about spies! The thing is there, it's free, it's just shut us down right under your nose! Why in God's name don't you do something?"
"Captain," Spock's voice said from behind them. "Will you come out and look at this, please?"
Kirk went out into the main tunnel to find the First Officer contemplating a side branch. "This is most curious," he said. "This tunnel is not indicated on any of the charts we were provided. It simply was not there before."
"Too recent to be on the maps, maybe?"
"Yes, but how did it get here, Captain? It shows no signs of having been drilled."
Kirk looked closer. "That's so. And the edges are fused. Could it be a lava tube?"
"That seems most unlikely," Spock said. "Had there been any vulcanism on this level since we arrived, everybody would be aware of it. And it joins a charted tunnel back there about fifty