Out on the street, in the dazzling sunshine of a warm Atlanta morning, a dozen young children were playing. Chasing, wrestling, and hugging each other, laughing and yelling, crazy and jubilant for no other reason than being alive on such a day. Inside the gleaming white building, though, behind double-glazed windows, the air was slightly chilly - the way John Shawcross preferred it - and nothing could be heard but the air-conditioning, and a faint electrical hum.

 The schematic of the protein molecule trembled very slightly. Shawcross grinned, already certain of success. As the pH displayed in the screen's top left crossed the critical value - the point at which, according to his calculations, the energy of conformation B should drop below that of conformation A - the protein suddenly convulsed and turned completely inside-out. It was exactly as he had predicted, and his binding studies had added strong support, but to see the transformation (however complex the algorithms that had led from reality to screen) was naturally the most satisfying proof.

 He replayed the event, backwards and forwards several times, utterly captivated. This marvellous device would easily be worth the eight hundred thousand he'd paid for it. The salesperson had provided several impressive demonstrations, of course, but this was the first time Shawcross had used the machine for his own work. Images of proteins in solution! Normal X-ray diffraction could only work with crystalline samples, in which a molecule's configuration often bore little resemblance to its aqueous, biologically relevant, form. An ultrasonically stimulated semi-ordered liquid phase was the key, not to mention some major breakthroughs in computing; Shawcross couldn't follow all the details, but that was no impediment to using the machine. He charitably wished upon the inventor Nobel Prizes in chemistry, physics and medicine; viewed the stunning results of his experiment once again, then stretched, rose to his feet, and went out in search of lunch.

 On his way to the delicatessen, he passed that bookshop, as always. A lurid new poster in the window caught his eye: a naked young man stretched out on a bed in a state of postcoital languor, one corner of the sheet only just concealing his groin. Emblazoned across the top of the poster, in imitation of a glowing red neon sign, was the book's title: A Hot Night's Safe Sex. Shawcross shook his head in anger and disbelief. What was wrong with people? Hadn't they read his advertisement? Were they blind? Stupid? Arrogant? Safety lay only in the obedience of God's laws.

 After eating, he called in at a newsagent that carried several foreign papers. The previous Saturday's editions had arrived, and his advertisement was in all of them, where necessary translated into the appropriate languages. Half a page in a major newspaper was not cheap anywhere in the world, but then, money had never been a problem.

 ADULTERERS! SODOMITES!

 REPENT AND BE SAVED!

 ABANDON YOUR WICKEDNESS NOW

 OR DIE AND BURN FOREVER!

 He couldn't have put it more plainly, could he? Nobody could claim that they hadn't been warned.

In 1981, Matthew Shawcross bought a tiny, run-down cable TV station in the Bible belt, which until then had split its air time between scratchy black-and-white film clips of fifties gospel singers, and local novelty acts such as snake handlers (protected by their faith, not to mention the removal of their pets' venom glands) and epileptic children (encouraged by their parents' prayers, and a carefully timed withdrawal of medication, to let the spirit move them). Matthew Shawcross dragged the station into the nineteen eighties, spending a fortune on a thirty-second computer-animated station ID (a fleet of pirouetting, crenellated spaceships firing crucifix-shaped missiles into a relief map of the USA, chiselling out the station logo of Liberty, holding up, not a torch, but a cross), showing the latest, slickest gospel rock video clips, "Christian" soap operas and "Christian" game shows, and, above all, identifying issues - communism, depravity, godlessness in schools - which could serve as the themes for telethons to raise funds to expand the station, so that future telethons might be even more successful.

 Ten years later, he owned one of the country's biggest cable TV networks.

 John Shawcross was at college, on the verge of taking up paleontology, when AIDS first began to make the news in a big way. As the epidemic snowballed, and the spiritual celebrities he most admired (his father included) began proclaiming the disease to be God's will, he found himself increasingly obsessed by it. In an age where the word miracle belonged to medicine and science, here was a plague, straight out of the Old Testament, destroying the wicked and sparing the righteous (give or take some haemophiliacs and transfusion recipients), proving to Shawcross beyond any doubt that sinners could be punished in this life, as well as in the next. This was, he decided, valuable in at least two ways: not only would sinners to whom damnation had seemed a remote and unproven threat now have a powerful, worldly reason to reform, but the righteous would be strengthened in their resolve by this unarguable sign of heavenly support and approval.

 In short, the mere existence of AIDS made John Shawcross feel good, and he gradually became convinced that some kind of personal involvement with HIV, the AIDS virus, would make him feel even better. He lay awake at night, pondering God's mysterious ways, and wondering how he could get in on the act. AIDS research would be aimed at a cure, so how could he possibly justify involving himself with that?

 Then, in the early hours of one cold morning, he was woken by sounds from the room next to his. Giggling, grunting, and the squeaking of bed springs. He wrapped his pillow around his ears and tried to go back to sleep, but the sounds could not be ignored - nor could the effect they wrought on his own fallible flesh. He masturbated for a while, on the pretext of trying to manually crush his unwanted erection, but stopped short of orgasm and lay, shivering, in a state of heightened moral perception. It was a different woman every week; he'd seen them leaving in the morning. He'd tried to counsel his fellow student, but had been mocked for his troubles. Shawcross didn't blame the poor young man; was it any wonder people laughed at the truth, when every movie, every book, every magazine, every rock song, still sanctioned promiscuity and perversion, making them out to be normal and good? The fear of AIDS might have saved millions of sinners, but millions more still ignored it, absurdly convinced that their chosen partners could never be infected, or trusting in condoms to frustrate the will of God!

 The trouble was, vast segments of the population had, in spite of their wantonness, remained uninfected, and the use of condoms, according to the studies he'd read, did seem to reduce the risk of transmission. These facts disturbed Shawcross a great deal. Why would an omnipotent God create an imperfect tool? Was it a matter of divine mercy? That was possible, he conceded, but it struck him as rather distasteful: sexual Russian roulette was hardly a fitting image of the Lord's capacity for forgiveness.

 Or - Shawcross tingled all over as the possibility crystalised in his brain - might AIDS be no more than a mere prophetic shadow, hinting at a future plague a thousand times more terrible? A warning to the wicked to change their ways while they still had time? An example to the righteous as to how they might do His will?

 Shawcross broke into a sweat. The sinners next door moaned as if already in Hell, the thin dividing wall vibrated, the wind rose up to shake the dark trees and rattle his window. What was this wild idea in his head? A true message from God, or the product of his own imperfect understanding? He needed guidance! He switched on his reading lamp and picked up his Bible from the bedside table. With his eyes closed, he opened the book at random.

 He recognised the passage at the very first glance. He ought to have; he'd read it and reread it a hundred times, and knew it almost by heart. The destruction of Sodom and Gomorrah.

 At first, he tried to deny his destiny: He was unworthy! A sinner himself! An ignorant child! But everyone was unworthy, everyone was a sinner, everyone was an ignorant child in God's eyes. It was pride, not humility, that spoke against God's choice of him.

 By morning, not a trace of doubt remained.

 Dropping paleontology was a great relief; defending Creationism with any conviction required a certain, very special, way of thinking, and he had never been quite sure that he could master it. Biochemistry, on the other hand, he mastered with ease (confirmation, if any was needed, that he'd made the right decision). He topped his classes every year, and went on to do a PhD in Molecular Biology at Harvard, then postdoctoral work at the NIH, and fellowships in Canada and France. He lived for his work, pushing himself mercilessly, but always taking care not to be too conspicuous in his achievements. He published very little, usually as a modest third or fourth co-author, and when at last he flew home from France, nobody in his field knew, or would have much cared, that John Shawcross had returned, ready to begin his real work.

 Shawcross worked alone in the gleaming white building that served as both laboratory and home. He couldn't risk taking on employees, no matter how closely their beliefs might have matched his own. He hadn't even let his parents in on the secret; he told them he was engaged in theoretical molecular genetics, which was a lie of omission only - and he had no need to beg his father for money week by week since, for tax reasons, twenty-five percent of the Shawcross empire's massive profit was routinely payed into accounts in his name.

 His lab was filled with shiny grey boxes, from which ribbon cables snaked to PCs; the latest generation, fully automated, synthesisers and sequencers of DNA, RNA, and proteins (all available off the shelf, to anyone with the money to buy them). Half a dozen robot arms did all the grunt work: pipetting and diluting reagents, labelling tubes, loading and unloading centrifuges.

 At first Shawcross spent most of his time working with computers, searching databases for the sequence and structure information that would provide him with starting points, later buying time on a supercomputer to predict the shapes and interactions of molecules as yet unknown.

 When aqueous X-ray diffraction become possible, his work sped up by a factor of ten; to synthesise and observe the actual proteins and nucleic acids was now both faster, and more reliable, than the hideously complex process (even with the best short-cuts, approximations and tricks) of solving Schrödinger's equation for a molecule consisting of hundreds of thousands of atoms.

 Base by base, gene by gene, the Shawcross virus grew.

As the woman removed the last of her clothes, Shawcross, sitting naked on the motel room's plastic bucket chair, said, "You must have had sexual intercourse with hundreds of men."

 "Thousands. Don't you want to come closer, honey? Can you see okay from there?"

 "I can see fine."

 She lay back, still for a moment with her hands cupping her breasts, then she closed her eyes and began to slide her palms across her torso.

 This was the two hundredth occasion on which Shawcross had paid a woman to tempt him. When he had begun the desensitising process five years before, he had found it almost unbearable. Tonight he knew he would sit calmly and watch the woman achieve, or skilfully imitate, orgasm, without experiencing even a flicker of lust himself.

 "You take precautions, I suppose."

 She smiled, but kept her eyes closed. "Damn right I do. If a man won't wear a condom, he can take his business elsewhere. And I put it on, he doesn't do it himself. When I put it on, it stays on. Why, have you changed your mind?"

 "No. Just curious."

 Shawcross always paid in full, in advance, for the act he did not perform, and always explained to the woman, very clearly at the start, that at any time he might weaken, he might make the decision to rise from the chair and join her. No mere circumstantial impediment could take any credit for his inaction; nothing but his own free will stood between him and mortal sin.

 Tonight, he wondered why he continued. The "temptation" had become a formal ritual, with no doubt whatsoever as to the outcome.

 No doubt? Surely that was pride speaking, his wiliest and most persistent enemy. Every man and woman forever trod the edge of a precipice over the inferno, at risk more than ever of falling to those hungry flames when he or she least believed it possible.

 Shawcross stood and walked over to the woman. Without hesitation, he placed one hand on her ankle. She opened her eyes and sat up, regarding him with amusement, then took hold of his wrist and began to drag his hand along her leg, pressing it hard against the warm, smooth skin.

 Just above the knee, he began to panic - but it wasn't until his fingers struck moisture that he pulled free with a strangled mewling sound, and staggered back to the chair, breathless and shaking.

 That was more like it.

The Shawcross virus was to be a masterful piece of biological clockwork (the likes of which William Paley could never have imagined - and which no godless evolutionist would dare attribute to the "blind watchmaker" of chance). Its single strand of RNA would describe, not one, but four potential organisms.

 Shawcross virus A, SVA, the "anonymous" form, would be highly infectious, but utterly benign. It would reproduce within a variety of host cells in the skin and mucous membranes, without causing the least disruption to normal cellular functions. Its protein coat had been designed so that every exposed site mimicked some portion of a naturally occurring human protein; the immune system, being necessarily blind to these substances (to avoid attacking the body itself), would be equally blind to the invader.

 Small numbers of SVA would make their way into the blood stream, infecting T-lymphocytes, and triggering stage two of the virus's genetic program. A system of enzymes would make RNA copies of hundreds of genes from every chromosome of the host cell's DNA, and these copies would then be incorporated into the virus itself. So, the next generation of the virus would carry with it, in effect, a genetic fingerprint of the host in which it had come into being.

 Shawcross called this second form SVC, the C standing for "customised" (since every individual's unique genetic profile would give rise to a unique strain of SVC), or "celibate" (because, in a celibate person, only SVA and SVC would be present).

 SVC would be able to survive only in blood, semen and vaginal fluids. Like SVA, it would be immunologically invisible, but with an added twist: its choice of camouflage would vary wildly from person to person, so that even if its disguise was imperfect, and antibodies to a dozen (or a hundred, or a thousand) particular strains could be produced, universal vaccination would remain impossible.

 Like SVA, it would not alter the function of its hosts - with one minor exception. When infecting cells in the vaginal mucous membrane, the prostate, or the seminiferous epithelium, it would cause the manufacture and secretion from these cells of several dozen enzymes specifically designed to degrade varieties of rubber. The holes created by a brief exposure would be invisibly small - but from a viral point of view, they'd be enormous.

 Upon reinfecting T-cells, SVC would be capable of making an "informed decision" as to what the next generation would be. Like SVA, it would create a genetic fingerprint of its host cell. It would then compare this with its stored, ancestral copy. If the two fingerprints were identical - proving that the customised strain had remained within the body in which it had begun - its daughters would be, simply, more SVC.

 However, if the fingerprints failed to match, implying that the strain had now crossed into another person's body (and if gender-specific markers showed that the two hosts were not of the same sex), the daughter virus would be a third variety, SVM, containing both fingerprints. The M stood for "monogamous", or "marriage certificate". Shawcross, a great romantic, found it almost unbearably sweet to think of two people's love for each other being expressed in this way, deep down at the subcellular level, and of man and wife, by the very act of making love, signing a contract of faithfulness until death, literally in their own blood.

 SVM would be, externally, much like SVC. Of course, when it infected a T-cell it would check the host's fingerprint against both stored copies, and if either one matched, all would be well, and more SVM would be produced.

 Shawcross called the fourth form of the virus SVD. It could arise in two ways; from SVC directly, when the gender markers implied that a homosexual act had taken place, or from SVM, when the detection of a third genetic fingerprint suggested that the molecular marriage contract had been violated.

 SVD forced its host cells to secrete enzymes that catalysed the disintegration of vital structural proteins in blood vessel walls. Sufferers from an SVD infection would undergo massive haemorrhaging all over their body. Shawcross had found that mice died within two or three minutes of an injection of pre-infected lymphocytes, and rabbits within five or six minutes; the timing varied slightly, depending on the choice of injection site.

 SVD was designed so that its protein coat would degrade in air, or in solutions outside a narrow range of temperature and pH, and its RNA alone was non-infectious. Catching SVD from a dying victim would be almost impossible. Because of the swiftness of death, an adulterer would have no time to infect their innocent spouse. The widow or widower would, of course, be sentenced to a life of celibacy, but Shawcross did not think this too harsh: it took two people to make a marriage, he reasoned, and some small share of the blame could always be apportioned to the other partner.

 Even assuming that the virus fulfilled its design goals precisely, Shawcross acknowledged a number of complications:

 Blood transfusions would become impractical until a foolproof method of killing the virus in vitro was found. Five years ago this would have been tragic, but Shawcross was encouraged by the latest work in synthetic and cultured blood components, and had no doubt that his epidemic would cause more funds and manpower to be diverted into the area. Transplants were less easily dealt with, but Shawcross thought them somewhat frivolous anyway, an expensive and rarely justifiable use of scarce resources.

 Doctors, nurses, dentists, paramedics, police, undertakers . . . well, in fact everyone, would have to take extreme precautions to avoid exposure to other people's blood. Shawcross was impressed, though of course not surprised, at God's foresight here: the rarer and less deadly AIDS virus had gone before, encouraging practices verging on the paranoid in dozens of professions, multiplying rubber glove sales by orders of magnitude. Now the overkill would all be justified, since everyone would be infected with, at the very least, SVC.

 Rape of virgin by virgin would become a sort of biological shot-gun wedding; any other kind would be murder and suicide. The death of the victim would be tragic, of course, but the near-certain death of the rapist would surely be an overwhelming deterrent. Shawcross decided that the crime would virtually disappear.

 Homosexual incest between identical twins would escape punishment, since the virus could have no way of telling one from the other. This omission irritated Shawcross, especially since he was unable to find any published statistics that would allow him to judge the prevalence of such abominable behaviour. In the end he decided that this minor flaw would constitute a necessary, token remnant - a kind of moral fossil - of man's inalienable potential to consciously choose evil.

It was in the northern summer of 2000 that the virus was completed, and tested as well as it could be in tissue culture experiments and on laboratory animals. Apart from establishing the fatality of SVD (created by test-tube simulations of human sins of the flesh), rats, mice and rabbits were of little value, because so much of the virus's behaviour was tied up in its interaction with the human genome. In cultured human cell lines, though, the clockwork all seemed to unwind, exactly as far, and never further, than appropriate to the circumstances; generation after generation of SVA, SVC and SVM remained stable and benign. Of course more experiments could have been done, more time put aside to ponder the consequences, but that would have been the case regardless.

 It was time to act. The latest drugs meant that AIDS was now rarely fatal - at least, not to those who could afford the treatment. The third millenium was fast approaching, a symbolic opportunity not to be ignored. Shawcross was doing God's work; what need did he have for quality control? True, he was an imperfect human instrument in God's hands, and at every stage of the task he had blundered and failed a dozen times before achieving perfection, but that was in the laboratory, where mistakes could be discovered and rectified easily. Surely God would never permit anything less than an infallible virus, His will made RNA, out into the world.

 So Shawcross visited a travel agent, then infected himself with SVA.

Shawcross went west, crossing the Pacific at once, saving his own continent for last. He stuck to large population centres: Tokyo, Beijing, Seoul, Bangkok, Manilla, Sydney, New Delhi, Cairo. SVA could survive indefinitely, dormant but potentially infectious, on any surface that wasn't intentionally sterilised. The seats in a jet, the furniture in a hotel room, aren't autoclaved too often.

 Shawcross didn't visit prostitutes; it was SVA that he wanted to spread, and SVA was not a venereal disease. Instead, he simply played the tourist, sight-seeing, shopping, catching public transport, swimming in hotel pools. He relaxed at a frantic pace, adopting a schedule of remorseless recreation that, he soon felt, only divine intervention sustained.

 Not surprisingly, by the time he reached London he was a wreck, a suntanned zombie in a fading floral shirt, with eyes as glazed as the multicoated lens of his obligatory (if filmless) camera. Tiredness, jet lag, and endless changes of cuisine and surroundings (paradoxically made worse by an underlying, glutinous monotony to be found in food and cities alike), had all worked together to slowly drag him down into a muddy, dreamlike state of mind. He dreamt of airports and hotels and jets, and woke in the same places, unable to distinguish between memories and dreams.

 His faith held out through it all, of course, invulnerably axiomatic, but he worried nonetheless. High altitude jet travel meant extra exposure to cosmic rays; could he be certain that the virus's mechanisms for self checking and mutation repair were fail-safe? God would be watching over all the trillions of replications, but still, he would feel better when he was home again, and could test the strain he'd been carrying for any evidence of defects.

 Exhausted, he stayed in his hotel room for days, when he should have been out jostling Londoners, not to mention the crowds of international tourists making the best of the end of summer. News of his plague was only now beginning to grow beyond isolated items about mystery deaths; health authorities were investigating, but had had little time to assemble all the data, and were naturally reluctant to make premature announcements. It was too late, anyway; even if Shawcross had been found and quarantined at once, and all national frontiers sealed, people he had infected so far would already have taken SVA to every corner of the globe.

 He missed his flight to Dublin. He missed his flight to Ontario. He ate and slept, and dreamt of eating, sleeping and dreaming. The Times arrived each morning on his breakfast tray, each day devoting more and more space to proof of his success, but still lacking the special kind of headline he longed for: a black and white acknowledgement of the plague's divine purpose. Experts began declaring that all the signs pointed to a biological weapon run amok, with Libya and Iraq the prime suspects; sources in Israeli intelligence had confirmed that both countries had greatly expanded their research programs in recent years. If any epidemiologist had realised that only adulterers and homosexuals were dying, the idea had not yet filtered through to the press.

 Eventually, Shawcross checked out of the hotel. There was no need for him to travel through Canada, the States, or Central and South America; all the news showed that other travellers had long since done his job for him. He booked a flight home, but had nine hours to kill.

"I will do no such thing! Now take your money and get out."

 "But -"

 "Straight sex, it says in the foyer. Can't you read?"

 "I don't want sex. I won't touch you. You don't understand. I want you to touch yourself. I only want to be tempted -"

 "Well, walk down the street with both eyes open, that should be temptation enough." The woman glared at him, but Shawcross didn't budge. There was an important principle at stake. "I've paid you!" he whined.

 She dropped the notes on his lap. "And now you have your money back. Good night."

 He climbed to his feet. "God's going to punish you. You're going to die a horrible death, blood leaking out of all your veins -"

 "There'll be blood leaking out of you if I have to call the lads to assist you off the premises."

 "Haven't you read about the plague? Don't you realise what it is, what it means? It's God's punishment for fornicators -"

 "Oh, get out, you blaspheming lunatic."

 "Blaspheming?" Shawcross was stunned. "You don't know who you're talking to! I'm God's chosen instrument!"

 She scowled at him. "You're the devil's own arsehole, that's what you are. Now clear off."

 As Shawcross tried to stare her down, a peculiar dizziness took hold of him. She was going to die, and he would be responsible. For several seconds, this simple realisation sat unchallenged in his brain, naked, awful, obscene in its clarity. He waited for the usual chorus of abstractions and rationalisations to rise up and conceal it.

 And waited.

 Finally he knew that he couldn't leave the room without doing his best to save her life.

 "Listen to me! Take this money and let me talk, that's all. Let me talk for five minutes, then I'll go."

 "Talk about what?"

 "The plague. Listen! I know more about the plague than anyone else on the planet." The woman mimed disbelief and impatience. "It's true! I'm an expert virologist, I work for, ah, I work for the Centres for Disease Control, in Atlanta, Georgia. Everything I'm going to tell you will be made public in a couple of days, but I'm telling you now, because you're at risk from this job, and in a couple of days it might be too late."

 He explained, in the simplest language he could manage, the four stages of the virus, the concept of a stored host fingerprint, the fatal consequences if a third person's SVM ever entered her blood. She sat through it all in silence.

 "Do you understand what I've said?"

 "Sure I do. That doesn't mean I believe it."

 He leapt to his feet and shook her. "I'm deadly serious! I'm telling you the absolute truth! God is punishing adulterers! AIDS was just a warning; this time no sinner will escape! No one!"

 She removed his hands. "Your God and my God don't have a lot in common."

 "Your God!" he spat.

 "Oh, and aren't I entitled to one? Excuse me. I thought they'd put it in some United Nations Charter: Everyone's issued with their own God at birth, though if you break Him or lose Him along the way there's no free replacement."

 "Now who's blaspheming?"

 She shrugged. "Well, my God's still functioning, but yours sounds a bit of a disaster. Mine might not cure all the problems in the world, but at least he doesn't bend over backwards to make them worse."

 Shawcross was indignant. "A few people will die. A few sinners, it can't be helped. But think of what the world will be like when the message finally gets through! No unfaithfulness, no rape; every marriage lasting until death -"

 She grimaced with distaste. "For all the wrong reasons."

 "No! It might start out that way. People are weak, they need a reason, a selfish reason, to be good. But given time it will grow to be more than that; a habit, then a tradition, then part of human nature. The virus won't matter any more. People will have changed."

 "Well, maybe; if monogamy is inheritable, I suppose natural selection would eventually -"

 Shawcross stared at her, wondering if he was losing his mind, then screamed, "Stop it! There is no such thing as 'natural selection'!" He'd never been lectured on Darwinism in any brothel back home, but then what could he expect in a country run by godless socialists? He calmed down slightly, and added, "I meant a change in the spiritual values of the world culture."

 The woman shrugged, unmoved by the outburst. "I know you don't give a damn what I think, but I'm going to tell you anyway. You are the saddest, most screwed-up man I've set eyes on all week. So, you've chosen a particular moral code to live by; that's your right, and good luck to you. But you have no real faith in what you're doing; you're so uncertain of your choice that you need God to pour down fire and brimstone on everyone who's chosen differently, just to prove to you that you're right. God fails to oblige, so you hunt through the natural disasters - earthquakes, floods, famines, epidemics - winnowing out examples of the 'punishment of sinners'. You think you're proving that God's on your side? All you're proving is your own insecurity."

 She glanced at her watch. "Well, your five minutes are long gone, and I never talk theology for free. I've got one last question though, if you don't mind, since you're likely to be the last 'expert virologist' I run into for a while."

 "Ask." She was going to die. He'd done his best to save her, and he'd failed. Well, hundreds of thousands would die with her. He had no choice but to accept that; his faith would keep him sane.

 "This virus that your God's designed is only supposed to harm adulterers and gays? Right?"

 "Yes. Haven't you listened? That's the whole point! The mechanism is ingenious, the DNA fingerprint -"

 She spoke very slowly, opening her mouth extra wide, as if addressing a deaf or demented person. "Suppose some sweet, monogamous, married couple have sex. Suppose the woman becomes pregnant. The child won't have exactly the same set of genes as either parent. So what happens to it? What happens to the baby?"

 Shawcross just stared at her. What happens to the baby? His mind was blank. He was tired, he was homesick . . . all the pressure, all the worries . . . he'd been through an ordeal - how could she expect him to think straight, how could she expect him to explain every tiny detail? What happens to the baby? What happens to the innocent, newly made child? He struggled to concentrate, to organise his thoughts, but the absolute horror of what she was suggesting tugged at his attention, like a tiny, cold, insistent hand, dragging him, inch by inch, towards madness.

 Suddenly, he burst into laughter; he almost wept with relief. He shook his head at the stupid whore, and said, "You can't trick me like that! I thought of babies back in '94! At little Joel's christening - he's my cousin's boy." He grinned and shook his head again, giddy with happiness. "I fixed the problem: I added genes to SVC and SVM, for surface receptors to half a dozen foetal blood proteins; if any of the receptors are activated, the next generation of the virus is pure SVA. It's even safe to breast feed, for about a month, because the foetal proteins take a while to be replaced."

 "For about a month," echoed the woman. Then, "What do you mean, you added genes . . . ?"

 Shawcross was already bolting from the room.

 He ran, aimlessly, until he was breathless and stumbling, then he limped through the streets, clutching his head, ignoring the stares and insults of passers-by. A month wasn't long enough, he'd known that all along, but somehow he'd forgotten just what it was he'd intended to do about it. There'd been too many details, too many complications.

 Already, children would be dying.

 He came to a halt in a deserted side street, behind a row of tawdry nightclubs, and slumped to the ground. He sat against a cold brick wall, shivering and hugging himself. Muffled music reached him, thin and distorted.

 Where had he gone wrong? Hadn't he taken his revelation of God's purpose in creating AIDS to its logical conclusion? Hadn't he devoted his whole life to perfecting a biological machine able to discern good from evil? If something so hideously complex, so painstakingly contrived as his virus, still couldn't do the job . . .

 Waves of blackness moved across his vision.

 What if he'd been wrong, from the start?

 What if none of his work had been God's will, after all?

 Shawcross contemplated this idea with a shell-shocked kind of tranquillity. It was too late to halt the spread of the virus, but he could go to the authorities and arm them with the details that would otherwise take them years to discover. Once they knew about the foetal protein receptors, a protective drug exploiting that knowledge might be possible in a matter of months.

 Such a drug would enable breast feeding, blood transfusions and organ transplants. It would also allow adulterers to copulate, and homosexuals to practise their abominations. It would be utterly morally neutral, the negation of everything he'd lived for. He stared up at the blank sky, with a growing sense of panic. Could he do that? Tear himself down and start again? He had to! Children were dying. Somehow, he had to find the courage.

 Then, it happened. Grace was restored. His faith flooded back like a tide of light, banishing his preposterous doubts. How could he have contemplated surrender, when the real solution was so obvious, so simple?

 He staggered to his feet, then broke into a run again, reciting to himself, over and over, to be sure he'd get it right this time: "ADULTERERS! SODOMITES! MOTHERS BREAST FEEDING INFANTS OVER THE AGE OF FOUR WEEKS! REPENT AND BE SAVED . . ."