To Kit and Karen

RUSTUM BATTACHARIYA: aka Bat, aka Megachirops, the Great Bat, reclusive problem-solver and Master of the Puzzle Network.

Jack Beston: the Ogre, head of SETI Project Argus.

Philip Beston: the Bastard, head of SETI Project Odin.

Sebastian Birch: displaced person after the Great War, with obsessive interest in outer planet cloud systems.

Dr. Valnia Bloom: head of the Ganymede Department of Scientific Research.

Janeed Jannex: displaced person after the Great War, and would-be Outer System colonist.

Magrit Knudsen: senior member of the Jovian Worlds cabinet, and former boss of Rustum Battachariya.

Captain Eric Kondo: captain of the Outer System Liner Achilles.

Hannah Krauss: senior SETI analyst, and boss of Milly Wu.

Harold (Hal) Launius: a leading nanotech designer.

Agatha Ligon: a Commensal, great-aunt to Alex Ligon and a member of Ligon Industries’ board of directors.

Alex Ligon: predictive modeler and junior member of the Ligon family.

Cora Ligon: great-aunt to Alex Ligon and a member of Ligon Industries’ board of directors.

Hector Ligon: cousin to Alex Ligon.

Juliana Ligon: cousin to Alex Ligon and a Commensal.

Karolus Ligon: uncle to Alex Ligon, and Ligon Industries’ senior “fix-it” specialist.

LenaLigon: mother of Alex Ligon and a Commensal.

Prosper Ligon: great-uncle to Alex Ligon and the head of Ligon Industries.

Tanya and Rezel Ligon: cousins to Alex Ligon.

Kate Lonaker: division chief for advanced planning and predictive modeling on Ganymede, and Alex Ligon’s immediate superior and lover.

Paul Marr: first officer of the Outer System Liner Achilles.

Christa Matloff: director of Earth’s orbiting medical facility.

Cyrus Mobarak: the “Sun King,” inventor of the Moby fusion drive, and head of Mobarak Enterprises.

Lucy-Maria Mobarak: daughter of Cyrus Mobarak.

MORD: the idiosyncratic high-level Fax of the late Mordecai Perlman.

Pack Rat: senior member and Master of the Puzzle Network.

OLE PEDERSEN: the capable but paranoid head of a predictive group competing with Alex Ligon and Kate Lonaker.

TheSeine: the integrated quantum-entangled computer system that extends all through the solar system.

Nadeen Selassie: legendary developer of a lost “dark as day” doomsday weapon, presumed killed at the end of the Great War.

Bengt Suomi: chief scientist for Ligon Industries.

Milly Wu: SETI analyst, and former junior champion of the Puzzle Network.

ZETTER: security chief for Project Argus.

The Great War was over. It ended four months after it began, when the leaders of the Belt — crushed, humiliated, drained, and defenseless — agreed to an unconditional surrender.

And yet the Great War did not end. It could not end. It had swept like a gigantic storm across the face of the solar system, and like any storm it left behind its own trail of destruction, invisible eddies of unspent energy, whirlpools of hatred, and cluttered heaps of flotsam: people, weapons, and secret knowledge thrown together and abandoned.

Mars was not aware of the fact, but although hard-hit it had been doubly blessed. True, over half of its people had died. But life could still continue far below the surface, and the same infernal forces that swept clear the northern hemisphere had set in motion the melting of the permafrost. Two thousand years later, humans would walk unaided on the surface and breathe the clear Mars air.

But that was far off, in a remote and unimaginable future. Today a gummy slick of microphages covered the land from equator to poles, waiting for anything with a GACT sequence that invited disassembly.

Night fell, for the seven hundred and fiftieth time since the end of the Great War. The stars came out, bright and steady in the black sky. Phobos raced across the heavens, west to east. The purblind phages were unaware of its presence, or of the rising of Jupiter and Saturn.

But others on Mars knew. Three hundred kilometers from the barren equator, in the dead center of a low, flat valley, a ten-meter circle of surface released into the thin air a mist of chemicals. Any GACT or GACU form would have died within milliseconds. The disassemblers were made of sterner stuff, but they knew enough to recognize danger. A wave of microphages surged backward, clearing an annulus of bare gray scree around the misted ring. Those disassembler phages unlucky enough to be caught within the ring writhed, retreated toward the middle, and withered to a small heap of desiccated powder.

A puff of warmer air from below dispersed their dust. In the center of the ring a black dot had appeared. The dot widened into a dark open disk, through which a fiat circular platform slowly rose. The microphages retreated farther, recoiling from the blown spray at the platform’s perimeter.

Two suited figures stood at the center of the platform. The woman was holding the hand of the little boy, and pointing upward. He was about four years old, and showed far more interest in the writhing circle of microphages and the bleak landscape beyond than in the starry sky.

“Do you see it?” The woman’s voice was wheezing and husky, and her back was oddly twisted. She shook the child’s hand impatiently. “You’re looking the wrong way. Over there. The brightest one.”

The boy was tall for his age, and sturdily built. He followed her pointing arm to the place where rising Jupiter hung above the eastern horizon. Dark eyes gleamed behind the suit’s visor, but his scowl was invisible in the dim light. “It’s not big. You said it would be big.”

“Jupiter is big. Huge. A lot bigger than this whole world. It only looks small because it’s so far away.”

“I could squash it in my fingers, it’s so little. It can’t hurt us.”

“It did hurt us. Jupiter looks tiny, but it’s really so big there are whole worlds, worlds nearly as big as this one, that circle around it. The people who live on them started the war. They were monsters. They killed your mother and father, and they killed your baby sister. They would have killed us, too, if we had stayed in the Belt. They are the reason we have to hide away here.”

It was an oft-told story, but the boy stared at Jupiter with greater interest. “I don’t see the other worlds at all.”

“They are there, just so far away you can’t see them. You’ve heard their names often. Ganymede, and Europa, and old Callisto.”

“And smoky smirky Io. You missed one. In the Gali-lo song there are four.”

“You’re right. And there really are four. But nobody lives on Io.”

“Why not? Does it have lots of these?” The boy’s arm waved toward the ring of microphages, standing like the curled lip of a breaking wave just beyond the protective spray.

“No. Io has lightning and burning hot and other bad things. Nobody can live there. You wouldn’t want to go there.”

“If Jupiter is so big, I’d like to live there.”

“You can’t do that, either. Jupiter is too big. It would crush you flat.”

“I bet it wouldn’t crush me. I’m strong. I’m stronger than you.”

“You are.” The woman tried to laugh, and it came out as a weak-lunged cough. “My dear, everyone is stronger than I am. The people up there who started the war didn’t kill me, but they certainly did their best. I used to be strong, too.”

A warning chime sounded in the suit helmets on her final words. The spray that held the phages at bay was thinning. The woman stared around her at the barren landscape, seeing changes there invisible to the boy.