"Quickly."

The door was mildewed with age, the wood so soft it crumbled. Inside the dim room, the windows had been blocked with ivy; as Jared lit lamps, Claudia stared around. "Just like home." He had set up his electron microscope on a rickety table, unpacked a few boxes of instruments and books.

He turned; in the flame light his face was haggard. "Claudia, you must look at this. It changes everything. Everything."

His anguish scared her. "Calm down," she said quietly. "Are you well?"

"Well enough." He leaned over the microscope, his long fingers adjusting it deftly. Then he stepped back. "You remember that scrap of metal I took from the study? Take a look at it."

Puzzled, she put her eye to the lens. The image was blurred; she refocused very slightly.

And then she went very still, so rigid that Jared knew she had seen, and in that instant, had understood.

He went and sat wearily on the floor, among the ivy and nettles, the Sapient robe wrapped around him, its hem trailing in the dirt. And he watched her as she stared.

IT WAS the Wall at the End of the World.

If Sapphique had truly fallen down it from top to bottom, h must have taken years. As Finn gazed up he felt the wind rebound from its immensity, making a slipstream that roared before them. Debris from the heart of Incarceron was blasted upward and then plummeted in an endless maelstrom; once trapped in that wind nothing would escape.

"We need to turn!" Gildas was staggering to the wheel; Finn scrambled after him.

Together they squeezed beside Keiro, hauling, trying to make the ship veer before she struck the updraft.

With the thunder, Lightsout came.

In the blackness Finn heard Keiro swear, felt Gildas struggle around him, holding on tight. "Finn. Pull the lever! In the deck."

His hand groped, found it, and he tugged.

Lights blinked on, two beams of light horizontal from the bow of the ship. He saw how close the Wall was. The discs of light played on huge rivets, bigger than houses, the bolted panels immense, battered by the impact of fragments, immeasurably cracked and scarred and corroded.

"Can we back out?" Keiro yelled.

Gildas threw him a glance of scorn. And in that instant they fell. Plunging down, spilling beams and spars and ropes, the ship dropped down the side of the Wall like a great silvery angel, the sails its flailing wings, shredding in seconds, until just as they thought she would break, the slipstream caught them. Mast snapping, the silver craft shot upward again, spinning uncontrollably, the headlights wheeling on the Wall, darkness, a rivet, darkness. Tangled in the ropes Finn clung on, grabbing an arm that might have been

Keiro's. The raging wind hurtled them high, the up-current welling from a roaring darkness, and as they rose the air thinned, the clouds and storm left far below, the Wall a sheer nightmare that sucked them close. They were so near, Finn could see its pitted surface was webbed with cracks and tiny doors, openings where bats gusted out and navigated the gale with ease. Scoured by the collision of a billion atoms the metal gleamed in the headlights.

The ship rolled. For a long second Finn was sure it would roll right over; he held on to Keiro and closed his eyes, but when he opened them it had righted, and Keiro was crashing against him, flailing in the ropes.

The stern swung around. There was a great slither, a tremendous jerk.

Gildas roared. "Attia! She's let the anchor go!"

Attia must have gone below and pulled the pins from the capstan. The ascent slowed, the sails shredding. Gildas hauled himself up and pulled Finn close. "We have to get right into the Wall, and jump."

Finn stared, blank. The Sapient snapped, "It's the only way out! The ship will fall and rise and tumble forever! We have to drive her in there!"

He pointed. Finn saw a dark cube. It jutted out from the beaten metal, a hollow opening of darkness. It looked tiny; their chance of entering it remote.

"Sapphique landed on a cube." Gildas had to hold on to him. "That has to be it!"

Finn glanced at Keiro. Doubt dickered between them. As Attia came up the hatchway and slid toward them, Finn knew his oathbrother thought the old man was crazy, consumed with his quest. And yet what choice did they have?

Keiro shrugged. Reckless, he spun the wheel and headed the ship straight at the Wall. In the headlights the cube waited, a black enigma.

CLAUDIA COULD not speak. Her astonishment, her dismay were too great. She saw animals.

Lions.

She counted them numbly; six, seven ... three cubs. A pride. That was the word, wasn't it...? "They can't possibly be real," she murmured.

Behind her, Jared sighed. "But they are."

Lions. Alive, prowling, one roaring, the rest snoozing in an enclosure of grass, a few trees, a lake where water birds waded.

She drew back, stared at the microscope, looked again.

One of the cubs scratched another; they rolled and fought. A lioness yawned and lay down, paws flat.

Claudia turned. She looked at Jared through the mothy lamplight and he looked back, and for a moment there was nothing to be said, only thoughts she didn't dare to think, implications she was too horrified to follow through.

Finally she said, "How small?"

"Incredibly small." He bit the ends of his long dark hair. "Miniaturized to about a millionth of a nanometer ... Infinitesimal."

"They don't... How do they stay ...?"

"It's a gravity box. Self-adjusting. I thought the technique was lost. It seems to be an entire zoo. There are elephants, zebra ..." His voice trailed off; he shook his head. "Perhaps it was the prototype ... trying it first on animals. Who knows?"

"So this means ..." She struggled to say it. "That Incarceron ..."

"We've been looking for a huge building, an underground labyrinth. A world." He stared ahead into the darkness. "How blind we've been, Claudia! In the library of the Academy there are records that propose that such things—trans-dimensional changes—were once possible. All that knowledge was lost in the War. Or so we thought."

She got up; she couldn't sit still. The thought of the lions tinier than an atom of her skin, the grass they lay on even smaller, the minute ants they crushed with their paws, the fleas on their fur ... it was too difficult to take in. But for them the world was normal. And for Finn ...?

She walked in nettles, not noticing. Made herself say, "Incarceron is tiny."

"I rear so."

"The Portal..."

"A process of entering. Every atom of the body collapsed." He glanced up and she saw how ill he looked. "Do you see? They made a Prison to hold everything they feared and diminished it so that its Warden could hold it in the palm of his hand. What an answer to the problems of an overcrowded system, Claudia. What a way to dismiss a world's troubles. And it explains much. The spatial anomaly. And there might be a time difference too, a very tiny one."

She went back to the microscope and watched the lions roll and play. "So this is why no one can come out." She looked up. "Is it reversible, Master?"

"How do I know? Without examining every—" He stopped dead. "You realize we have seen the Portal, the gateway? In your father's study there was a chair."

She leaned back against the table. "The light fixture. The ceiling slots."

It was terrifying. She had to walk again, pace up and down, think about it hard. Then she said, "I have something to tell you too. He knows. He knows we have the Key."