The door at the far end of the lowest chamber opened an hour after the valve was patched. Orison gave no reason. It said, “The forge has written down your repair. The next chamber is open to you. Only the next. I apologize for the rest,” and the door slid aside, and beyond it there was light.
Mara stood on the red paint in the doorway and could not move.
The second chamber was enormous. It was round, a great hollow drum of a room, so tall that its ceiling was lost in shadow and so wide that the far wall was a pale curve in the distance. A walkway ran out from the door, a narrow bridge of grated steel with a rail on either side and a strip of red paint down its middle, and it ran straight out over nothing toward the center of the drum and stopped, short of the center, at a small round platform.
Beyond the platform, at the very center of the room, hanging in the air, was the heart.
It was not large. That surprised her more than anything. After the rivers of light outside the lift shaft, after the scale of the cargo ring and the lamp city and the endless rails, she had expected the heart to be a mountain. It was perhaps the size of a cart wheel. A sphere, roughly, though not perfectly round; its surface was patterned, ridged and channeled, like the surface of a walnut or a brain, a mass of folded metal the color of old pewter. It hung in the air with nothing holding it.
Around it, rings of fire.
Pale rings of light, white and faintly blue, circling the heart at different angles, slowly, the way the hands of a clock circle, but in three directions at once: one ring around its equator, one tilted, one almost upright. They turned and crossed and turned, and where they passed close to the heart’s surface the folded metal glowed faintly along its channels, as though the light were running through it.
And through the heart, from top to bottom, a split.
It was black. Absolutely black, the black of the strip, the black that light went into and did not come out of. It ran through the heart’s folded surface in a perfectly straight line, from the top of the sphere to its bottom, dividing it into two unequal parts. Mara could see the rings’ light passing over the split and vanishing into it, a gap in the glow.
It was straight. That was the thing. Nothing in the heart was straight; everything was curved and folded and channeled. And through it ran this line, as straight as a ruled line on a page, as straight as a blade.
“Don’t step off the paint,” Sera said, behind her.
Mara stepped onto the walkway. Sera came after her, the line between them. They walked out over the drop toward the platform, slowly, their boots on the red strip, their hands on the rails, and the rails were cold, and the suits drew the cold in.
At the platform, Mara stopped. She was perhaps four meters from the heart. Close enough to see the texture of its folds, and to feel, faintly, on her face through the visor, the warmth that came off the rings. Close enough to hear it. The graft had been humming since the door opened, low, rising, and now, this close, it was a sound like many voices singing very quietly in a room next door.
She took out her notebook.
She drew the split. She did it the way she would draw a crack on a casting for Tavin: the line first, top to bottom, then its edges, carefully, because the edges told you more than the line. The split was not clean at the edges. Where the black met the pewter, the metal had a texture. Fine ridges, running away from the split on both sides, at right angles to it, like the grain of wood around a cut, or the teeth of a comb.
“Forty seconds,” Sera said.
Mara looked up.
“Since you touched the rail at the door,” Sera said. She had her watch up in front of her visor. “Forty seconds. Write that down too.”
Mara wrote it. 40 s from rail. She knew why without asking. Somewhere in notebook I, on the page of symptoms, her mother had written: judgment goes before strength. Sera was counting so that Mara did not have to.
She went back to the edges.
The fine ridges ran away from the split in straight lines. All in the same direction. Every one of them, on both sides of the split, pointing away from it, as if the metal had been combed. She had seen metal crack from stress a thousand times in the yard, and it never looked like this. A stress crack wandered. It followed the weak places in the grain, branched, forked, stopped and started. Its edges were ragged. The grain around it was disturbed in every direction, the way a pane of glass shatters around a stone.
This was not that. This metal had not cracked. Its grain had been turned. Every crystal along the line had been aligned the same way, all at once, as though something had reached into the heart and told the grain to part along this line, and the grain had obeyed.
“Orison,” Mara said.
“Yes.”
“What happened to the heart?”
“The heart was retired,” Orison said.
“Retired.”
“That is the word in my record. Retired.” A pause, a soft crackle. “I cannot say by whom. The record of the retirement is in a part of my memory I cannot reach. I have the word. I do not have the hand.”
Mara looked at the split. At its straight black line and its combed edges.
“Then the split isn’t damage,” she said. “It’s a cut.”
“Cuts have people behind them,” Sera said.
She said it flatly, the way she had said alive is the only one I can fly, and Mara heard it land in the great round room and go out into the dark above them.
Mara measured it. She had no rule long enough, so she used the rail: she sighted along the walkway rail toward the heart and counted the rail’s joints, and estimated the split’s length against them. Then she looked at the heart’s channels, the folds that ran over its surface like veins, and followed them with her eyes, one at a time, to see where they went.
They all went to the split. Every channel she could see, every fold that carried the rings’ light across the heart’s surface, ran into the black line and stopped. The split crossed all of them. Not one channel ran unbroken from one side of the heart to the other.
“It crosses every channel,” she said slowly. “Every load channel. All of them.”
“What does that mean?” Sera asked.
“It means you can’t patch it.” Mara lowered the notebook. “If it crossed one channel, you could bridge that one. Two, maybe. But every channel? There’s nothing left to bridge from. The whole heart is cut through.” She looked at it, hanging in its rings, glowing along its useless folds. “It needs a replacement. A new heart.”
“Made of what?”
Mara thought of the Founder plate on Tavin’s bench, the band of rust-colored ink around the inner shell. Dusk iron. Condenses along the cooling inner shell of a failing lamp. Nine hours. Whoever’s standing in the lamp when it dies.
“Dusk iron,” she said. “From the inner shell. This lamp’s inner shell.” She looked up into the dark above the heart, as though she could see through the drum’s ceiling to the shell beyond it. “Lorn is failing. So the dusk iron will be there. Condensing. On the shell.”
“And you’d have to go and get it.”
“Somebody would.”
Sera kept quiet.
Mara turned and looked back along the walkway at the door they had come through, at the lowest chamber beyond it with its patched valve and its bench and its vise. A workshop. Small and cold, but a workshop, with a bench and a vise and a supply of measured cold that would hold at a quarter open.
“The lowest chamber,” she said. “That’s where I’ll work. Whatever I bring down from the shell. I’ll set it up there.”
“Fine,” Sera said. “Then let’s go back to it.”
Mara did not move.
She turned back to the heart. The rings were turning. The many quiet voices in the graft were murmuring in the room next door, rising and falling. And under them, close, coming from the split itself, from the black line where the light went in and never came out, there was another sound. Fainter. Different. She could not make it out.
She leaned toward it. Only a little. Toward the heart, over the platform’s rail, close enough to hear the rings hum against her visor.
Behind her, Mara felt the rescue line go taut. Sera’s hand had closed on it.