"List of revealed behavioral scores. Gender-based. Huh." I stare. Sex with your partner gets five points for the very first occurrence, dropping off to one point each time after a while. In other words, it's a decay function. "Adultery," that bad word, gets minus one hundred. There are some other crazy items. Getting pregnant brings fifty points, bringing the baby to term brings another fifty. What's abortion? Whatever it is, it gets hammered as hard as adultery, which is what got Esther and Phil into—let's not go there. There are other things here, the most improbable activities, that get huge penalties. But rape isn't mentioned. Murder loses you just seventy points. What kind of sense does that make? It's ludicrous! "Either they're trying to generate a psychotic polity, or the people in the society they derived these scores from were off their heads."

"Or possibly both." Sam yawns. "Listen, it's late. We need to get some sleep. Why don't we go to bed and chew this over tomorrow? With the others?"

"Yes." I put the tablet down, not mentioning that tomorrow I've got other plans because Fiore is visiting the library again. "Tomorrow is going to be a very interesting day."

I spend a long time lying in bed awake, fantasizing about what I'd like to do to Mick, about what I think he deserves to have done to him—but which isn't going to happen. I finally drift into sleep after a particularly brutal fantasy, and I dream again, but this time it's no nightmare. Rather, it's a flashback to how I started my life as a tank. I guess these flashbacks would be nightmarish, if they were still invested with any emotional impact—instead they're grisly and freighted with significance, but drained of immediacy by time and necessity.

I stay aboard the MASucker Grateful for Duration for almost a gigasecond as it crawls slowly through interstellar space. There's not really anything else I can do—we've been offlined by Curious Yellow, which appears to have targeted the ship for special treatment on the basis of its self-contained systems. Half-crazy with worry for my family, tempered by apprehension about my situation, I check myself into one of the ship's assemblers when it becomes clear that this isn't a temporary outage, that something vast and extremely ugly has overcome the Republic of Is and there's no way around it. We won't find out what's happening until the Grateful for Duration reaches its next destination, an obscure religious retreat in orbit around a small and very cold gas giant that orbits a brown dwarf about thirty trillion kilometers away. I extract a promise from Kapitan Vecken that he'll unserialize me if anything interesting happens, then archive myself to backup storage for the duration.

When I blink and awaken in the A-gate, the universe has changed around me. I've been asleep for a gigasecond while we crawled across almost three Urth-style "light years," then spent a megasec decelerating under high-gee conditions to a rendezvous with Delta Refuge. The contemplatorian monastery has been erased and filed in deep storage, bits and atoms reconfigured into the sinister angled constructs of a military-industrial complex. Kapitan Vecken is reluctant to lend his ship to the resistance cabal, but he's happy to run off a clone of his stand-alone A-gate to help speed their botched, jerry-built attempts at constructing a sterile, uninfected nano-ecosystem. And he's happy to put me ashore. So I meet the resistance.

At that time—when I first join them—the Linebarger Cats are an informal group of refugees, dissidents, and generally uncooperative alienists who resent any attempt to dictate their conscious phase space. They live in a few cramped habs with little attempt to conceal the artificiality of the environment. In my first few kiloseconds the close-lipped paramilitaries who insist on searching me as I climb out of the transfer pod explain what I've missed. The infection is a history worm. It infiltrates A-gates. If you go into an infected A-gate, it crudely deletes chunks of your memory (mostly at random, but if you remember anything from before the Republic of Is, you're likely to lose it). Then it copies its own kernel into your netlink. There are some bootstrap instructions. If you find an uninfected gate, there's a compulsion to put it into operator debugging mode, enter commands via the conversational interface, then upload yourself. At which point the A-gate executes the infected boot loader in your netlink, copies it into its working set, and—bang!—another infected gate.

Assemblers are an old established technology, and for many gigaseconds they've been a monoculture, best-of-breed, all using the same subsystems—if you want a new A-gate, you just tell the nearest assembler to clone itself. Where Curious Yellow got started we do not know, but once it was in the wild, it spread like an ideal gas, percolating through the network until it was everywhere.

It takes a while for a worm to overrun an A-gate network while in stealth mode, using human brains as the infective vector, but once the infection reaches critical mass, it's virtually impossible to stop it spreading throughout an entire polity.

Once the activation signal is sent, everything speeds up. Suddenly, there are privileged instruction channels. Infected A-gates sprout defenses, extrude secure netlinks to the nearest T-gates, and start talking to each other directly to exchange orders and information. Here's the fun thing about Curious Yellow—A-gates that are infected can send each other message packets, peer to peer. If you've got the right authentication keys, you can send a distant gate running Curious Yellow instructions to make things. Or modify things. Or change people as they pass through it. It's an anything box.

Fearful weapons appear, seemingly at random, engaged on search and destroy missions for who knows what. Someone, somewhere, is writing the macros, and the only way to stay clear is to sever all T-gate connections, shutting the rogue assemblers off from their orders. But the A-gates are still infected, still running Curious Yellow. And if you use them to make more A-gates, those will be infected, too, even if you write complete new design templates—Curious Yellow's payload incorporates a pattern recognizer for nanoreplicators and inserts itself into anything that looks even remotely similar. The only solution is to drop back to prereplicator tech, use the infected gates to make dumb tools, then try to rebuild a sterile assembler from the wreckage of post-Acceleration technosystems.

Or you can surrender to Curious Yellow and try to live with the consequences, as the Linebarger Cats explain to me in words of one syllable. Then they ask me what I intend to do, and I ask if I can sign up.

Which explains how I ended up as a tank, but not really why.

I wake up as the bright light of dawn crosses the edge of my pillow. I stretch and yawn and look at Sam sleeping beside me, and for a heart-stoppingly tender moment I long to be back on the outside, where I'm Robin and she's Kay and we're both properly adjusted humans who canbe whoever we want to be and do whatever we want to do. For a moment I wish I'd never found out who he was . . .

So I force myself to get out of bed. It's a library day, and I need to be there because I've got at least one customer to deal with—Fiore. I'm tired and apprehensive, wondering in the cold light of day if I've blown everything. The idea of going through a normal working cycle after what happened last night feels bizarre, the sort of thing a zombie would do—as if I'm entirely a creature of unconscious habit, obedient to the commands of an unknown puppeteer. But there's more to it than just doing the job, I remind myself. I've got a different goal in mind, something else that the day job is just a cover for. I'm still not entirely sure what's going on here, why I was sent, and who Yourdon and Fiore are, but enough stuff has surfaced that I can make an educated guess, and the picture I'm piecing together isn't pretty.