They probed deeper, out of communication with the rest of the company back beyond the ring of dead troopers and with the fleet far overhead. They were on their own, as far as they knew, searching for the answers that would end the problems created by the Citadel.
The interior of the tunnel got lighter as they pushed in deeper. The fungus was growing thicker but it was never very bright. From deeper, farther inside the Citadel was a dull pounding, suggesting the workings of the internal machinery. And there was an overwhelming surge of electrical energy. Monier felt it smashing into her, blanking out the impressions she was receiving from the Citadel's rock and stone outer walls.
Hyland caught her and asked, "Are we getting close?"
"Close to what?" asked Monier. She had to concentrate on the words to understand them. The air felt as if it was charged with enough power to light a city.
"The source of the power... to any of the creatures who live in here?"
"I don't know. I can't tell."
"Shit," said Coolledge. "This is doing this no good."
"Shut up," said Price.
Monier sat back and leaned against the stone. She rubbed her temples. "There is nothing around us. No beings of any kind. There were once, but no more. They programed this thing to take care of itself just as they programed the ship to be independent of communication with them."
"So they're not using this part of the Citadel. Maybe it's storage," said Coollege.
"No," said Monier, "you don't understand. Long ago there was someone in here... very long ago, but no more. There is nothing here."
"Storage," repeated Coollege.
"If it is empty," said Price, "It might be easy to sabotage this section of it."
"How?" asked Hyland. "I haven't seen any wires to yank out or printed circuits to smash. Nothing but this stone tunnel that seems to lead nowhere."
"So what do we do?" asked Monier.
"I think we move a little deeper into this thing and see if there isn't something we can do to break it."
"You sure that there is no one in here?" asked Price.
"No, sir. It's empty."
"That makes this a giant computer?" asked Coollege. "A system that someone left on when they abandoned the planet?"
"It's not abandoned," said Price thinking of the creatures they had seen putting in the pipeline. And then he understood it all. They were the maintenance team, grown to keep the Citadel functioning, just as the little alien had been on the asteroid to keep it functioning. Sometimes there was nothing better for a chore than a flesh and blood hand. The Citadel grew the creatures to preform those tasks that it couldn't do for itself.
In that moment he understood the true nature of the evil that they faced. Not an alien race but an alien machine that recognized nothing but its own existence. Everything was created to serve it. The machine had by-passed humanity and become a god. The universe existed for it. Or the planet did.
"Tree?" asked Coollege. "What's wrong?"
"This thing," he said. "This thing is completely wrong. We have to destroy it."
"How?" asked Coollege.
"I don't know, but we can't leave until we find that answer. "This thing must be destroyed.
"We move deeper and see if there isn't something vulnerable inside it," said Hyland.
"That's not much of a plan," said Price.
"Yeah," agreed Hyland, "but at the moment it's the only one we've got."