The air smelled funny, and the yellow-white glow in the walls dimmed and brightened irregularly. Best get back to their pressure suits, soon.

Chmeee said, “There is the lander. It would function as a spacecraft.”

“What do you call a spacecraft? It must have interplanetary capability. It’d need that to get around on the Ringworld. I wouldn’t think we could reach another star with it.”

“I was thinking of ramming Needle. If there is no escape, we may take vengeance.”

“That’ll be fun to watch. You ramming a General Products hull.”

The kzin loomed over him. “Do not be too amusing, Louis. What would I be on the Ringworld, with no mate, no land, no name, and a year to live?”

“We’d be buying time. Time to find a way off. In the meantime”—Louis stood up—“officially, we’re still searching for a magic transmutation machine. Let’s make at least a token search.”

Louis woke ravenous. He dialed a cheddar cheese souffl‚ and Irish coffee and blood-oranges and ate his way through it all.

Chmeee slept curled protectively around himself. He looked different somehow. Neater—yes, neater, because the scar tissue under his fur had disappeared and the new fur was growing out.

His stamina was impressive. They had searched every one of the four Ringworlder ships, then moved on to a long, narrow building at the very lip of infinity, which proved to be the guidance center for the spacecraft accelerator system. At the last, Louis was moving in a fog of exhaustion. He knew he should have been examining Needle for details of construction, weak points, routes into the flight deck. Instead he had watched Chmeee, with hatred. The kzin never stopped to rest.

The Hindmost appeared from somewhere, from behind or within the green-painted private sector. His mane was combed and fluffy, dressed with crystals that changed their spectral color as he moved. Louis was intrigued. The puppeteer had been scruffy while he was flying Needle alone. Did he dress to impress his alien prisoners with his elegance?

He asked, “Louis, do you want the droud?”

Louis did, but—“Not yet.”

“You slept eleven hours.”

“Maybe I’m adjusting to Ringworld time. Did you get anything done?”

“I took laser spectrograms of the ships’ hulls. They are largely iron alloys. I have deep-radar scans, two views each for the four ships; I moved Needle while you slept. There are two more spaceport ledges one hundred and twenty degrees around the Ringworld. I located eleven more ships by their hull composition. I could not learn detail at this distance.”

Chmeee woke, stretched, and joined Louis at the transparent wall. “We learn only to ask more questions,” he said. “One ship was left intact, three were stripped. Why?”

“Perhaps Halrloprillalar could have told us,” the Hindmost aid. “Let us deal with the only urgent question. Where is the transmutation device?”

“We have no instruments here. Flick us to the lander, Hindmost. We will use the screens on the flight deck.”

Eight screens glowed around the horseshoe curve of the lander’s instrument board. Chmeee and Louis studied ghostly schematics of the Bussard ramjet ships, generated by the computer from the deep-radar scans.

“It looks to me,” Louis said, “like one team did the entire looting job. They had three ships to work with, and they took what they wanted most first. They kept working till something stopped them: they ran out of air or something. The fourth ship came later. Mmm … but why didn’t the fourth crew loot their own ship?”

“Trivialities. We seek only the transmuter. Where is it?”

Chmeee said, “We could not identify it.”

Louis studied the deep-radar ghosts of four ships. “Let’s be methodical. What isn’t a transmutation system?” He traced lines on the image of the one intact ship, using a light-pointer. “Here, these paired toroids circling the hull have to be the ramscoop field generators. Fuel tanks here. Access tubes here, here, here …” As he pointed them out, the. Hindmost obliged by removing sections of ship from the screen. “Fusion reaction motor, this whole section. Motors for the landIng legs. Take out the legs too. Attitude jets here, here, here, all fed by tubes along here carrying plasma from the one small fusion generator, here. Battery. This thing with the snout, pointing out of the middle of the hull—what did Prill call it?”

“Cziltang brone,” Chmeee sneezed. “It softens the Ringworld floor material temporarily, for penetration. They used it instead of airlocks.”

“Right.” Louis continued, with enthusiasm and hidden glee. “Now, they probably wouldn’t keep the magic transmuter in the living quarters, but … sleeping rooms here, control rooms here, here, here, the kitchen—”

“Could that be—”

“No, we thought of that. It’s just an automated chemistry lab.”

“Proceed.”

“Garden area here. Sewage treatment feeds in. Airlocks …”

When Louis had finished, the ship was gone from the screen. The Hindmost patiently restored it. “What did we overlook? Even if the transmuter was dismounted, removed, there would be space for it.”

This was getting to be fun. “Hey, if they really kept their fuel outside—lead, molded around the hull—then this isn’t really an inboard hydrogen tank, Is it? Maybe they kept the magic transmuter in them. It needed heavy padding or heavy insulation … or cooling by liquid hydrogen.”

Chmeee asked, before the Hindmost could, “How would they remove it?”

“Maybe with the cziltang brone from another ship. Were all the fuel tanks empty?” He looked at the ghosts of the other ships. “Yah. Okay, we’ll find the transmuters on the Ringworld … and they won’t be working. The plague will have got to them.”

“Halrloprillalar’s tale of the bacterium that eats superconductor is in our records,” the Hindmost said.

“Well, she really couldn’t tell us an that much,” said Louis. “Her ship left on a long tour. When it came back, there was no more Ringworld civilization. Everything that used superconductors had stopped.” He had wondered how much to believe of Prill’s tale of the Fall of the Cities. But something had destroyed the Ringworld’s ruling civilization. “Superconductor is almost too wonderful. You end up using it in everything.”

“Then we can repair the transmuters,” said the Hindmost.

“Oh?”

“You will find superconducting wire and fabric stored aboard the lander. It is not the same superconductor the Ringworld used. The bacterium will not touch it. I thought we might need trade goods.”

Louis kept his poker face intact, but the Hindmost had made a startling statement. How did puppeteers come to know so much about a mutant plague that killed Ringworld machines? Suddenly Louis didn’t doubt the bacterium at all.

Chmeee hadn’t caught it. “We want to know what the thieves used for transportation. If the rim-wall transport system failed, then our transmuters may be just the other side of the rim wall, abandoned there because they stopped working.”

Louis nodded. “Failing that, we’ve got a lot of territory to search. I think we should be looking for a Repair Center.”

“Louis?”

“There has to be a control and maintenance center somewhere. The Ringworld can’t run itself forever. There’s meteor defense, meteor repair, the attitude jets … the ecology could go haywire—it all has to be watched. Of course the Repair Center could be anywhere. But it’s got to be big. We shouldn’t have that much trouble finding it. And we’ll probably find that it’s been abandoned, because if anyone had been minding the store, he wouldn’t have let the Ringworld slide off center.”

The Hindmost said, “You have been putting your mind to this.”

“We didn’t do too well the first time we came here. We came to explore, remember? Some kind of laser weapon shot us down, and we spent the rest of our time trying to get off alive. We covered maybe a fifth of the width, and learned just about nothing. It’s the Repair Center we should have been looking for. That’s where the miracles are.”