The cart squeaked as she pushed it along the corridor. It was probably from the wheels. She concentrated on the wheels, on how one or more of them must be rubbing on the cheap bushings, not lubricated properly when built and not made to be oiled later. That knowledge, that memory of where the screeching sounds came from, kept them from turning into the wails of her sisters, her mother, her grandmother. Especially her grandmother, whose sack of charms and fetishes she carried in her apron now.

Her fingers whitened as she gripped the cart's handle. The handle was smooth and rounded: it didn't feel at all like the underside of the rusty bed frame she had clutched, hidden by her grandmother seconds before the door was kicked in. The glasses and bottles on the cart clattered, and she knew they didn't sound at all like the jingling of opened buckles, of keys in khaki pockets above her.

After today, those sounds wouldn't be coming to her again.

Completed, programmed, prototype-tested, with timers and key-codes set, several thousand stage-one factories emerge from the generator (a slowly pulsing, slick mass in a plastic washtub, cables trailing over the edge to a stained sheet-metal case) and drip into the cheap but well-washed cup. Carried out of the shack, they cascade into the bin, then begin their twin tasks of staying on the surface of the heap and reproducing. They get the energy easily enough from the kitchen scraps and poultry offal.

After a few days, the factories have multiplied a millionfold, forming a gossamer layer of low-energy activity covering the heap. Every housefly that alights, then arises, journeying onward over the capital's barrio shanties and government palaces, carries tens of thousands of them on her feet.

I was no happier than I had to be about meeting the Colonel. The Embassy staff, our overt personnel, should have handled it better. Reports were that he was close to panic over the rumors (well-founded, to be sure) that we might be abandoning him or, worse, backing the rebels ourselves. The eventual outcome was obvious, to him as well as to us: his army, his party, the structure he had put together, piece by piece over the decades, was about to slide apart.

On the plus side, reports depicted him as frightened not just for his power but for his wealth and life. When I actually saw him, on his blusterful arrival in the conference room, those accounts of his attitude were vindicated: he kept gulping mineral water and, to my amazement, surreptitiously biting his nails. I stifled a smile as I remembered my uncle, the realty broker, and his favorite phrase: "motivated seller."

By the end of the session, with a crew of women clearing away the refreshments (our Embassy's people felt he'd be further cowed by the insult of having servants traipse in before we were done with him, but he was in fact too frightened to notice), we had extracted an agreement for elections in six months' time. For once, it was a deal we could make him honor. He thanked me, in fact, when I openly guaranteed safety to his property and person.

I waited a few seconds before adding that the offer naturally included his family and personal staff.

He looked surprised, then agreed.

The menial who was clearing off the table raised her head and gazed at him then. I was the only one who saw her stare, but I knew we all felt what she felt. After a moment, she saw me observing her and resumed her work, sweeping his nail-bitings and other small debris off the table top with her hand before wiping away spilled water and the sweat from his hands. Back upstairs, I felt something I thought I'd grown out of years before: the urge to shower immediately after negotiating with a head of state.

Once attached to a fly's feet, the stage-one factories do nothing but hang on, unless certain narrow chemical conditions arise in their surroundings. Even so, some mistakenly let go of their flies, responding to the traces of sweat on abandoned shoes or scraps of paper. They destroy themselves trying to burrow through cellulose or cloth to non-existent blood vessels, dying by the microgram all over the capital.

Of course, millions of others, in hundreds of places, actually sink through real skin and arrive in real veins. And those are just from the first day's batch.

She and the others were summoned back to the conference room later than she expected, but she was surprised to see them still in their chairs. Obviously, the crew was expected to clear away the water bottles and glasses while the talks continued.

Logistically, the officials' presence made no difference to her plans and hopes, but seeing his face again took the breath out of her. She had searched those features over the decades, in her memory and later on posters or television screens, trying to see the outward signs of monstrosity. But she always saw only the congenial face of a man like any other, somehow separate from the acts of the mind that crouched behind the unremarkable eyes.

She gathered her thoughts and started to work, moving around the table, standing the glasses inverted on the tray as the men spoke. She knew they assumed English was opaque to the servants, but was still glad to learn that the patrons were gently untying the strings from this particular puppet. Though she knew that no "peaceful transition of power" would affect his fate, it was good that his party's legitimacy would meet its own distinct demise. The organization's own members would dismantle the structure once it became clear they could expect no more sustenance from its trough.

Still, at one point his inhumanity made her stare at him with loathing. She started when she felt eyes on her, from one of the "diplomats." Turning involuntarily to face the man, she cursed her foolish reflex: it was Morris, who'd run against her in the Graduate Student Assembly at U.C.L.A. Before she'd completed her doctorate, before she went home and realized what she could do with her learning.

Morris, however, glanced away immediately, showing no sign of recognition. He obviously didn't remember her at that moment; she could only pray he wouldn't later on.

Again, she pulled herself together and continued.

Her plan had been to make sure that the one glass, the one with the smears she needed to pull apart and learn, would be the only one she would lay sideways on the tray. But she was overjoyed to see that he still bit his nails deeply, harrowing the flesh of his fingertips, just as he had when he'd left the ruined hut.

Not so much swimming as surfing, the factories circulate in a multitude of bloodstreams. When they can, they attach themselves to vessel walls and extract nuclei from the host cells. They are looking for a password. Each rooted factory tries five times, reading DNA from five different nearby cells. After five failures, it simply falls apart, dispersing as hundreds of more or less inert molecules that will wash from the system via the kidneys.

Eventually, of course, a few thousand of the factories get lucky.

On the plane home, during a nap, the buswoman's face came back to me. I saw her lips move and put words to the picture -­ stirring words about the need for better wheelchair access to a new nanotechnology lab. Starting awake, I realized I'd been dreaming about -- well, what was her name? The one who beat me in that student-government runoff.

I nod back off, vaguely ashamed at my reptile-brain's assertion that they all look alike.

The few thousand factories that score, that find the code they seek, finally begin the real work. They pull what they need from the cells and plasma sluicing past them and fill their remaining time manufacturing the stage-two factories: the ones that can swim. These start moving along the bloodstream, stopping every tenth of a second to sample the code again, then continuing. After completing one hundred twenty-eight consecutive matches (usually in just under fifty seconds), each spends about two minutes making one hundred twenty-eight converters. Every stage-two factory will continue this conditional sequence ‹ swimming, matching, making ‹ until the environment no longer supports it.

Like the stage-one factories (which have all destroyed themselves by now, all, each one, over the whole of the country, from ocean to Gulf, because a certain date has passed according to their hard-coded internal clocks), the converters can't swim. They can only drift along, until they meet or enter what they're meant to convert.

It took her longer than she had hoped, but not as long as she had allowed for. So she still had weeks before the elections, plenty of time to nail down the codon sequences, to reconstruct work lost during the frequent slum power failures, plenty of time to make sure there would be enough flies.

She especially had time to laugh with her grandmother's memory, as she looked at the faded bruja sack hung on the wall above the assembler tub. "I couldn't get any hair, hah? But this is good enough." Better, in fact: she'd known since her undergrad days that hair is a dead excretion and holds no genetics, but the nail-bitings she'd taken were attached to those tiny remnants of flesh, with the helices folded within.

The converters inevitably lodge against, and inside of, their target material and begin debasing it, creating free ions of carbon and molecules of metallic calcium. It's a difficult process, requiring energy from the motion of blood plasma, and ultimately wearing down ‹ destroying ‹ the converters. Each can only disassemble about a millionth of a gram before it works itself to pieces.

Ultimately, the stage-two factories' environment -- the bloodstream itself -- has degraded so much that it can't support the manufacture of any more converters.

And once the blood stops flowing, of course, the converters are no longer carried into the bones, and they simply wait for a few minutes before shutting down forever.

The first reports were surprising only because poisoning is such a rare form of assassination these days. Bombs and sniper fire are the preferred methods, even when the attackers don't care about getting away. Our analysts expected the palace's security staff to uncover the plot via the usual methods, employed with gross or subtle brutality on the kitchen help. Likewise we anticipated his recovery, once the substance was identified and countermeasures taken, especially once he arrived in a black-budget clinic up here.

But then he died after all. I saw the photos, his proudly bemedalled hospital gown tangled in the flaccid puddle of flesh that his corpse had become. I also was briefed on the nature of the microbes found in the remains: the billions of uncomplicated machines, etching at the internal structure of every bone almost atom by atom until what remained collapsed of its own weight, their genesis clear in principle but mysterious in specifics.

I asked about isolating possible carriers; the specialists laughed. One told me "we've narrowed it down to something he must have touched, swallowed, or inhaled." An airborne vector, in fact, is the favored guess. They are all certain, however, that this was keyed only to him: "Otherwise, everybody from Medellin to the Yucatan would be melting as we speak." I remember the sweat dripping from his terrified face to the conference table, his teeth working at his fingers.

When I wondered at their lack of concern over the method's novelty, the smiles broadened. A physician replied, "What we've learned from this so far has already saved years of work for an entire-- " She stopped herself from telling me something I might not be cleared to know. "Anyway, years of work."

All the regional hands are visibly glad he's gone. Maybe our organization has changed, or maybe it's just that he was an embarrassment, a horror-movie clown invoked near the beginning of every Senate appropriations debate.

I fly down and advise his lieutenant to release the cooks, telling him that we believe the perpetrator to be long gone and untraceable. (We've made no progress on the search, in fact; I'm pretty sure we won't, either, as long as I keep my own counsel.) The man is sweating with fear, certain his master's death is our doing. I deny it but he doesn't believe me; I am content, for once, to let one of these people think us all-powerful.

The next day, our ambassador appears before their National Assembly. His speech guardedly, codedly, but unmistakably supports the reform parties in the upcoming elections.

I watch him talk and remember once more her hand, trembling as she swept the nail-bitings into a used water glass, and her eyes, jerking instantly away when she caught me looking at her. I can't know for sure whether I saw fear in her face after that or whether I just remember it that way. I wonder if she knows my name, or if that even matters compared to everything she must know about me and everyone else who sat at that table. I wonder if it will be her who cleans up the leavings from our first meeting with the next regime.

I wonder if I'll be able to find out, since I don't plan to be in the room.

Copyright 2000, Angus MacDonald