She hated coffee. She thought Louis must be insane to swallow the bitter stuff, and she told him so.

The shower was a long lost, badly missed luxury, once Louis explained the controls.

She went wild over the sleeping plates.

Speaker was celebrating the homecoming in his own fashion. Louis didn't know everything about the kzin's stateroom. He did know that the kzin was eating his head off.

"Meat!" Speaker exulted. "I was not happy eating long-dead meat."

"That stuff you're eating now is reconstituted."

"Yes, but it tastes freshly killed!"

That night Prill retired to a couch in the lounge. She appreciated the sleeping field, but not for sleeping. But Louis Wu slept in free fall for the first time in three months.

He slept ten hours, and woke feeling like a tiger. A half-disc of sun flamed beneath his feet

Back aboard the Improbable, he used the flashlight-laser to free the knobbed end of the shadow square wire. When he finished, it still had some fused electrosetting plastic attached.

He did not try to carry it to the Liar. The black thread was far too dangerous, the Ring floor far too slippery. Louis moved on all fours on the frictionless surface, and he pulled the knob behind him.

He found Speaker silently watching from the airlock.

Louis entered the airlock via Prill's stepladder, pushed past the kzin and went aft. Speaker continued to watch.

The farthest point aft in the wreck of the Liar was a channel the size of a man's thigh. It had passed wiring to machinery in the Liar's wing, when the Liar had had a wing. Now it was sealed by a metal hatch. Louis opened the hatch, tossed the knobbed end of the wire through and outside.

He moved forward. At intervals he checked the position of the wire by using it to slice a Jinxian sausage dialed from the Liar's kitchen. Then he marked the spot with bright yellow paint. When he finished, the path of the virtually invisible thread was marked in a line of yellow splotches running through the Liar.

When the wire drew taut, it would certainly cut through some internal partitions of the ship. The yellow paint allowed Louis to gauge the path it would take, and to assure himself that the wire would not damage any part of the life-support system. But the paint had another purpose. It would warn them all to keep away from the wire, lest they lose fingers or worse.

Louis left the airlock, waited for Speaker to follow him out. Then he closed the outer door. 

At this point Speaker asked, "Is this why we came?" 

"Tell you in a minute," said Louis. He walked aft along the General Products hull, picked up the knob in both hands, and tugged gently. The wire held.

He put his back into it. He pulled with all his strength. The wire did not budge. The airlock door held it fast.

"There's just no way to give it a stronger test. I wasn't sure the airlock door would be a close enough fit. I wasn't sure the wire wouldn't abrade a General Products hull. I'm still not sure. But yes, this is why we came." 

"What shall we do next?"

"We open the airlock door." He did it. "We let the thread slide freely through the Liar while we carry the handle back to the Improbable and cement it in place." And they did that.

The thread that had linked the shadow squares trailed invisibly away to starboard. It had been dragged for thousands of miles behind the Improbable, because there was no way to get it aboard the flying building. Perhaps it trailed all the way back to the tangle of thread in the City Beneath Heaven; a tangle like a cloud of smoke, that might have held millions of miles of the stuff.

Now it entered the Liar's double airlock, circled through the Liar's fuselage, out the wiring channel, and back to a blob of electrosetting plastic on the underside of the flying building.

"So far so good," said Louis. "Now I'll need Prill. No, tanj it! I forgot. Prill doesn't have a pressure suit." 

"A pressure suit?"

"We're taking the Improbable up Fist-of-God Mountain. The building isn't airtight. We'll need pressure suits, and Prill doesn't have one. We'll have to leave her here."

"Up Fist-of-God Mountain," Speaker repeated. "Louis, one flycycle has not the power to drag the Liar up that slope. You propose to burden the motor with the additional mass of a floating building."

"No, no, no. I don't want to drag the Liar. All I want to do is pull the shadow square wire behind us. It should slide freely through the Liar, unless I give Prill the word to close the airlock door."

Speaker thought about it. "That should work, Louis. If the puppeteer's flycycle has not the power we need, we can cut away chunks of the building to make it lighter. But why? What do you expect to find at the top?"

"I could tell you in one word; and then you'd laugh in my face. Speaker, if I'm wrong, I swear you'll never know," said Louis Wu.

And he thought: I'll have to tell Prill what to do. And plug the Liar's wiring channel with plastic. It won't stop the thread from sliding, but it should make the Liar nearly airtight.

The Improbable was not a spaceship. Her lifting power was electromagnetic, thrusting against the Ring foundation itself. And the Ring floor sloped up toward Fist-of-God; for Fist-of-God was hollow. Naturally the Improbable tended to tilt, to slide back down against the push of the puppeteer's flycycle.

To that problem, Speaker had already found the answer.

They were living in pressure suits before the journey had properly begun. Louis sucked pap through a tube, and thought yearningly of steak broiled with a flashlight-laser. Speaker sucked reconstituted blood, and thought his own thoughts.

They certainly didn't need the kitchen. They cut that part of the building loose, and improved the tilt of the building to boot.

They cut away air conditioning and police equipment. The generators that had ruined their flycycles went only after they had been positively identified as separate from the lifting motors. Walls went. Some walls were needed for their shade; for heating became a problem in the direct sunlight.

Day by day they neared the crater at the top of Fist-of-God, a crater that would have swallowed most asteroids. The lip of the crater looked like no impact crater Louis had ever seen. Shards like obsidian spearheads formed a jagged ring. Spearheads the size of mountains themselves. There was a gap between two such peaks . . . they could enter there . . .

"I take it," said Speaker, "that you wish to enter the crater itself."

"That's right."

"Then it is good that you noticed the pass. The slope above is too steep for our drive. We should reach the pass very soon."

Speaker was steering the Improbable by modifying the flycycle thrust. That had been necessary since they cut away the stabilizing mechanism in a final attempt to reduce the building's weight. Louis had grown used to the bizarre appearance of the kzin: the five transparent concentric balloons of his pressure suit, the fishbowl helmet with its maze of tongue controls half hiding the kzin's face, the tremendous backpack.

"Calling Prill," Louis said into the intercom. "Calling Halrloprillalar. Are you there, Prill?"

"I am."

"Stay there. We'll be through in twenty minutes."

"Good. You've been long enough at it."

The Arch seemed to blaze above them. A thousand miles above the Ringworld, they could see how the Arch merged into the rim walls and the flat landscape. Like the first man in space, a thousand years ago, looking down on an Earth that, by Jahweh and his mighty hammer, really was round.

"We couldn't have known," said Louis Wu, not loudly. But Speaker looked up from his work.

Louis didn't notice the kzin's odd look. "It would have saved us so much trouble. We could have turned back after we found the shadow square wire. Tanj, we could have dragged the Liar straight up Fist-of-God Mountain behind our flycycles. But then Teela wouldn't have met Seeker."

"The luck of Teela Brown again?"

"Sure." Louis shook himself. "Have I been talking to myself?"

"I have been listening."

"We should have known," said Louis. The gap between the sharp peaks was very near. He felt the urge to babble. "The Engineers would never have built a mountain this high here. They've got over a billion miles of thousand-mile-high mountains, if you count both rim walls."

"But Fist-of-God is real, Louis."

"No, no, no. It's just a shell. Look down; what do you see?"

"Ringworld foundation material."

"We thought it was dirty ice when we first saw it. Dirty ice, in hard vacuum! But forget that aspect. Remember the night you explored a giant map of the Ringworld? You couldn't find Fist-of-God. Why not?"

The kzin didn't answer.

"It wasn't there, that's why not. It wasn't there when the map was made. Prill, are you there?"

"I am here. Why would I leave you?"

"Good. Close the airlock doors. Repeat, close the airlock doors now. Don't cut yourself on the thread."

"My people invented this thread, Louis." Prill's voice was garbled with static. She was off for a minute, then: "Both doors are closed."

The Improbable was passing between the standing shards of mountain. Tense as Louis was, he would have been still more tense; but subconsciously he was expecting a kind of canyon or pass between those peaks.

"Louis, just what do you expect to find in Fist-of-God crater?"

"Stars," said Louis Wu.

The kzin was tense too. "Do not mock me! In all honor—"

—And they were through. There wasn't any pass. There was only a broken eggshell of Ringworld foundation material, stretched by terrific stresses to a few feet of thickness; and beyond that, the crater in Fist-of-God Mountain.

They were falling. And the crater was full of stars.

Louis Wu had an excellent imagination. In his mind's eye the event was perfectly clear.

He saw the system of the Ringworld, sterile, tidily clean, empty of ramships, empty but for a G2 star and a daisy chain of shadow squares and the Ringworld.

He saw a foreign body passing near, too near. He watched its hyperbolic fall from interstellar space, and he saw its path interrupted—by the underside of the Ringworld.

In his vision the foreign body was about the size of the Earth's Moon.

It must have been ionized plasma in the first seconds. A meteorite can be cooled by ablation, by the boiling away of its own skin. But here the vaporized gas could not expand; it had forced its way into a deforming pocket of the Ringworld floor. The landscape had deformed upward, its carefully planned ecology and rainfall patterns shot to hell over a region greater than the surface of the Earth. All that desert . . . and Fist-of-God itself, raised a full thousand miles upward before the incredibly tough Ring floor ripped to let the fireball through.

Fist-of-God? Tanj, yes! Watching from a Ringworld prison cell, Louis Wu had seen it clear in his mind's eye. It must have been visible clear to both rims: a ball of hellfire the size of the Earth's Moon ripping up through the floor of the Ringworld like a strong man's fist through a cardboard box.

The natives could be thankful that the Ring floor had deformed as much as it did. The hole was easily big enough to let all the air out of the Ringworld; but it was a thousand miles too high . . .

The crater was full of stars.

And there wasn't any gravity; there wasn't anything for the lifting motors to push against. Louis hadn't really thought this far ahead.

"Grab something," he bellowed, "and hang on! If you fall through the bay window, there'll be no rescue."

"Naturally not," said Speaker. He was wrapped around a naked metal beam. Louis had found another.

"Was I right? Stars!"

"Yes, Louis, but how did you know?"

There was gravity, a steady, heavy pull on the Improbable. The skeleton of a building turned on its side, and the bay window was up.

"It's holding," Louis said fiercely. He wriggled to get right side up on the beam. "It better! I hope Prill strapped down; she'll have a bouncy ride. Up the side of Fist-of-God Mountain, riding at the end of ten thousand miles of shadow square wire. Up and over the lip, then—"

They looked up at the underside of the Ringworld. An infinity of sculptured surface. In the middle, a tremendous conical meteor puncture, shiny at the bottom. As the Improbable swung like a plumb bob beneath the Ringworld, the sun flashed suddenly in the bottom of the crater.

"—Out and down. Then we'll be tied to the Liar, and the Liar will be on its way to clear space at 770 miles per second. Plenty of time for the wire to pull us together; but if that doesn't work, we've got the thruster motor in Nessus's flycycle.

"How did I know? I've been telling you that. Didn't I mention the landscape?"

"No."

"That was the clincher. All the peaks of foundation material showing through the rock, and the fall of civilization only fifteen hundred years old! It was because those two asteroid punctures had fouled up the wind patterns. Do you realize that most of the traveling we did was between those two punctures?"

"Very indirect reasoning, Louis."

"It worked."

"Yes. And so I will live to see another sunset," the kzin said softly.

Louis felt an electric thrill. "You too?"

"Yes, I watch sunsets on occasion. Let us speak of the Long Shot."

". . . What did you say?"

"If I could steal the Long Shot from you, my kind would dominate known space until a stronger species impinged on our expanding sphere. We would forget all we have learned so painfully, regarding cooperation with alien species."

"True," Louis said into the dark. The pull from the stolen shadow square wire was steady now. The Liar must be well on its way up Fist-of-God's ten degree slope.

"We might not get that far, while the luck of many Teela Browns protects Earth. Yet honor would compel me to make the attempt," said Speaker-To-Animals. "How could I lead my species away from the honorable path of war? The kzinti gods would revile me."

"I warned you about playing god. It hurts."

"Fortunately the difficulty does not arise. You have said that I would destroy the Long Shot if I tried to take it. The risk is too great. We will need the puppeteer hyperdrive to escape the wave front from the Core explosion."

"True enough," said Louis. The kzin would back into the nearest gravity well if he tried to take the Long Shot into hyperdrive. Knowing that, Louis asked, "But suppose I were lying?"

"I could not hope to outwit a being of your intelligence."

Sunfire flashed again in Fist-of-God crater.

"Think how short a way we came," said Louis. "One hundred and fifty thousand miles in five days, the same distance back in two months. A seventh of the short way across the Ringworld. And Teela and Seeker think they're going the long way round."

"Fools."

"We never saw the rim wall. They will. I wonder what else we missed? If the Ringworld ramships got as far as Earth, they may have picked up some blue whales and sperm whales, before we made them extinct. We never got out onto the ocean.

"The people they'll meet. There's no end to the ways a culture can go. And the room . . . the Ringworld's so big . . ."

"We can't go back, Louis."

"No, of course not."

"Not until we can deliver our secret to our respective worlds. And acquire an intact ship."

Larry Niven