Louis pulled on a flexible one-piece suit, skintight, and attached the fishbowl helmet and backpack. It was standard equipment; the suit would pass sweat, letting the body be its own cooling system. Louis added a loose oversuit lined in silver. It would be cold out there.

The airlock was built for three. Good: Louis could picture times when he wouldn’t want to wait outside while an airlock cycled for someone else. If the Hindmost wasn’t expecting emergencies, he had prepared for them anyway. As air was replaced by vacuum, Louis’s chest expanded. He pulled shut the “girdle,” the wide elastic band around his middle that would help him exhale.

Chmeee strode out of the lander, out of Needle, into the night. Louis picked up a tool kit and followed at an easy jog.

The sense of freedom was heady, dangerous. Louis reminded himself that his suit’s communication link included the Hindmost. Things had to be said, and soon, but not in the puppeteer’s hearing.

Proportions were wrong here. The half-disassembled ships were too big. The horizon was too close and too sharp. An infinite black wall cut the brilliant, half-familiar starscape in half. Seen through vacuum, the shapes of distant objects remained sharp and clear up to hundreds of thousands of miles away.

The nearest Ringworld ship, the intact one, looked to be half a mile distant. It was more like a mile. On the last voyage he had constantly misjudged the scale of things, and twenty-three years hadn’t cured him.

He arrived puffing beneath the huge ship, to find an escalator built into one landing leg. The ancient machinery wasn’t working, of course. He trudged up.

Chmeee was trying to work the controls of a big airlock. He fished a grippy out of the kit Louis carried. “Best not to burn through doors yet,” he said. “There is power.” He pried a cover off and worked at the innards.

The outer door closed. The inner door opened on vacuum and darkness. Chmeee turned on his flashlight-laser.

Louis was a little daunted. This ship would probably carry enough people to fill a small town. Easy to get lost here. “We want inspection tubes,” he said. “I’d like to get the ship pressurized. With that big helmet you couldn’t get into an access tube built for men.”

They turned into a corridor that curved with the curve of the hull. There were doors just taller than Louis’s head. Louis opened some of the doors. He found small living cubicles with bunks and pull-down chairs for humanoids his own size and smaller.

“I’d say Halrloprillalar’s people built these ships.”

Chmeee said, “We knew that. Her people built the Ringworld.”

“That they did not do,” said Louis. “I wondered if they built the ships or took them over from someone else.”

The Hindmost spoke in their helmets. “Louis? Halrloprillalar told you her people built the Ringworld. Do you think she lied?”

“Yes.”

“Why?”

She’d lied about other things. Louis didn’t say so. He said, “Style. We know they built the cities. All those floating buildings, they’re the kind of thing you put up to show off your wealth and power. Remember the sky castle, the floating building with the map room in it? Nessus took back tapes.”

“I studied them,” said the puppeteer.

“And it had a raised throne and a wire sculpture of someone’s head that was as big as a house! If you could build a Ringworld, would you bother with a sky castle? I don’t believe it. I never believed it.”

“Chmeee?”

The kzin said, “We must accept Louis’s judgment on human matters.”

They turned right into a radial corridor. Here were more sleeping rooms. Louis inspected one in detail. The pressure suit was interesting. It was mounted against a wall like a hunter’s trophy hide: one piece, crisscrossed with zippers, all open. Instantly accessible in case of vacuum.

The kzin waited impatiently while Louis zipped it shut and stepped back to study the effect.

The joints bulged. Knees and shoulders and elbows like cantaloupes, hands like a fistful of walnuts strung together. The face jutted forward; there were power and air-reserve gauges set below the faceplate.

The kzin growled, “Well?”

“Nope, I need more proof. Let’s go.”

“More proof of what?”

I think I know who built the Ringworld … and why the natives are so much like humans. But why would they build something they couldn’t defend? It doesn’t make sense.”

“If we discussed it—”

“Nope, not yet. Come on.”

At the ship’s axis they found pay dirt. Half a dozen radial corridors converged, and a tube with a ladder led up and down. There were diagrams covering four sections of wall, with labels that were tiny, detailed pictograms.

“How convenient,” said Louis. “It’s almost as if they had us in mind.”

“Languages change,” said the kzin. “These people rode the winds of relativity; their crews might be born a century apart. They would have needed such aids. We held our empire together with similar aids, before the Wars With Men. Louis, I find no weaponry section.”

“There was nothing guarding the spaceport either. Nothing obvious, anyway.” Louis’s finger traced the diagrams. “Galley, hospital, living area—we’re here in the living area. Three control centers; seems excessive.”

“One for the Bussard ramjet and interstellar space. One for fusion drive and maneuvering in an occupied system, and weapons control, if any. One for life support: this one, that shows wind blowing through a corridor.”

The Hindmost spoke. “With transmutation, they would use a total conversion drive.”

“Oh, not necessarily. A blast of radiation that powerful would play merry hell in an inhabited system,” said Louis. “Hah! There are our access tubes, going to … ramscoop generators, fusion motor, fuel feed. We want the life-support controls first. Two flights up and that way.”

The control room was small: a padded bench facing three walls of dials and switches. A touchpoint in the doorjamb caused the walls to glow yellow-white, and set the dials glowing too. They were unreadable, of course. Pictograms segregated the controls into clusters governing entertainment, spin, water, sewage, food, air.

Louis began flipping switches. The ones most often used would be large and easy to reach. He stopped when he heard a whistling sound.

The pressure dial at his chin rose gradually.

There was low pressure at 40 percent oxygen. Humidity was low but not absent. No detectable noxious substances.

Chmeee had deflated his suit and was stripping it off. Louis removed his helmet, dropped the backpack, and peeled his suit away, all in unseemly haste. The air was dry and faintly stale.

Chmeee said, “I think we may start with the access tube to the fuel feed. Shall I lead?”

“Fine.” Louis heard in his voice the tension and eagerness he’d tried to repress. With luck the Hindmost would miss it. Soon, now. He followed the kzin’s orange back.

Out the door, turn right into a radius, follow to the ship’s axis and down a ladder, and a great furry hand engulfed Louis’s upper arm and pulled him into a corridor.

“We must talk,” the kzin rumbled.

“Yah, and about time too! If he can hear us now, we might as well give up. Listen—”

“The Hindmost will not hear us. Louis, we must capture Hot Needle of Inquiry. Have you given thought to this?”

“I have. It can’t be done. You made a nice try, but what the futz were you going to do next? You can’t fly Needle. You saw the controls.”

“I can make the Hindmost fly it.”

Louis shook his head. “Even if you could stand guard over him for two years, I think the life-support system would break down, trying to keep you both alive that long. That’s the way he planned it.”

“You would surrender?”

Louis sighed. “All right, let’s look at it in detail. We can offer the Hindmost a credible bribe or a credible threat, or we can kill him if we think we can fly Needle afterward.”