If you think it's embarrassing to get a hysterical fit of the giggles with one of your best friends in Salisbury's wines and spirits department, try having your mobile phone ring in the middle of it. Now that's really excruciat¬ing. At least when it's someone as laconic as Gizmo, you don't have to destroy your street cred totally by having a conversation. A series of grunts signifying "yes" and "no" will do just fine. I gathered he'd got the info I wanted and he was about to stuff it through my letter box unless I had any serious objections. I didn't. Even if it was Police Harassment Week and Linda Shaw and her sidekick were back on my doorstep, they could hardly arrest Gizmo for impersonating a postman.

Being midweek and midmorning, we were through the checkouts in less time than it takes to buy a newspaper in our local corner shop. Delia and I hugged farewell in the car park and went our separate ways, each intent on mak¬ing some criminal's life a misery. "Talk to Josh," were her final words.

Gizmo had done me proud. Not only had he translated the files into a format I could easily read on my computer, but he'd also printed out hard copies for me. As far as her patient notes were concerned, Sarah Blackstone's passion for secrecy had been superseded by a medical training that had instilled the principle of always leaving clear notes that another doctor could follow through should you be murdered by a burglar between treatments. I flicked through until I found the file relating to Alexis and Chris. Not only were their names correct on the printout, but also phone numbers at home and work, address and dates of birth. Which meant the chances were high that all the other patients' details were accurate. If ever I needed to interview any of them, I knew where to start looking.

At one level, the job Alexis had hired me to do was now complete. I had checked out the consulting rooms and removed any evidence that might lead back to Sarah Blackstone's patients. But what I had were only backup copies. The originals were still out there somewhere, pre¬sumably sitting on the hard drive of the laptop that the doc¬tor had used throughout her consultations. If Gizmo had cracked their file protection, it was always possible that the police had someone who could do the same thing. It was also possible that whoever had killed Sarah Black-stone had stolen her computer and was sitting on the best blackmail source since Marilyn Monroe's address book. Women who could afford this treatment could afford payoffs too. The game was a long way off being over.

What I needed now was more information. I under¬stood very little of the patient notes sitting in front of me and I understood even less of the fertility technology that I was dealing with here. I needed to know what technical backup Sarah Blackstone had needed, and just how diffi¬cult it was to achieve what she had done. I also needed to know if this was something she could do alone, or if she'd have had to involve someone else. Time to beg another favor from someone I already owed one to. Dr. Beth Taylor is one of the legion of women who have been out with Bill Mortensen without managing to accomplish what an Australian boutique bimbo had pulled off. Beth works part-time in an inner-city group practice where nobody's had to pay a prescription charge in living memory. The rest of the time she lectures on ethics to medical students who think that's a county in the south of England. If she feels like a bit of light relief, she does the odd bit of free¬lance work for us when we're investigating medical insur¬ance claims.

I tracked Beth down at the surgery. I didn't tell her about Bill's planned move. It wasn't that I thought it would hurt her feelings; I just couldn't bear to run through it yet again. Once we'd got the social niceties out of the way, I said, "Test-tube babies."

She snorted. "You've been reading too many tabloids. IVF, that's what you call it when you want a bit of respect from the medical profession. Subfertility treatment, when you want to impress us with your state-of-the-art consciousness. What are you after? Treatment or information?"

"Behave," I said scathingly.

"I know someone at St. Mary's. He used to be a research gynecologist, now he works part-time in the subfertility unit. I bring him in to do a seminar on my course on the ethics of interference with human fertility."

"Would he talk to me?" I asked.

"Probably. He likes to show off what a new man he is. Nothing he loves more than the chance to demonstrate to a woman how sensitive he is to our reproductive urges. What is it you want to know, and why?"

"I need the five-minute crash course in IVF for beginners and a quick rundown on where the leading edge is right now. What can and can't be done. I'm not asking for anything that isn't readily available in the literature, I just need it in bite-sized pieces that a lay person can understand."

"Gus is your man, then. You didn't mention why this sudden interest?"

"That's right, I didn't. Is he going to want a reason?"

Beth thought for a moment. "I think it might be as well if you were a journalist. Maybe looking for nonattributable background for a piece you're doing following women's experiences of being treated for subfertility?"

"Fine. How soon can you fix it?"

"How soon do you need it?"

"I'm free for lunch today," I said. The devil finds work for idle hands; if you can't manage any other exercise, you can always push your luck.

"So I'll lie. I'll tell him you're young, gorgeous, and single. Gus Walters, that's his name. I'll get him to call you."

Ten minutes later, my phone rang. It was Gus Walters. Young, gorgeous, and single must have worked. I hoped he wouldn't be too disappointed. Two out of three might not be bad, but none ain't good. "Thanks for getting back to me so quickly," I said.

"No problem. Besides, I owe Beth a favor, and this seemed like a very cheap way of repaying it." Yes, it was definitely a doctor.

"Are you free for lunch today? I know it's short notice ..."

"If you can meet me at half past twelve at the front entrance, I can give you an hour and you can buy me a curry," he said.

"Deal. How will I know you?" I asked.

"Oh, I think I'll know you," he said, voice all dark brown smoothness. Definitely a doctor.

It's a constant source of amazement to me that the staff at Manchester's major hospital complex don't all have seri¬ous weight problems. They're only five minutes walk from the Rusholme curry parade, as serious a selection of Asian restaurants as you'll find anywhere in the world. If I worked that close to food that good, cheap, and fast, I couldn't resist stuffing my face at least twice a day. Richard might be convinced that the Chinese were the only people on earth with any claim to culinary excel¬lence, but for me, it was a dead heat with the chefs of the subcontinent. Frankly, as soon as I was seated at a window table with a menu in front of me, I was a lot more inter¬ested in the range of pakoras than in anything Gus Wal¬ters could possibly tell me.

He was one of the nonrugby-playing medics: medium height, slim build, shoulders obviously narrow inside the disguise of a heavy, well-cut tweed jacket. His hands were long and slender, so pale they looked as if they were al¬ready encased in latex. Facially, he had a disturbing resemblance to Brains, the Thunderbirds' puppet. Given that he'd opted for the identical haircut and very similar large-framed glasses, I wondered if he had enough sense of irony to have adopted them deliberately. Then I remembered he was a doctor and dismissed the idea. He probably thought he looked like Buddy Holly.

On the short walk to the nearest curry house, we'd done the social chitchat about how long we'd lived in Manchester and what we liked most and least about the city. Now I wanted to get the ordering done with so we could cut to the chase. I settled for chicken pakora followed by karabi gosht with a garlic nan. Gus opted for onion bhajis and chicken roganjosh. He grinned across the table at me and said, "The orifice I get closest to doesn't bother about garlic breath." It rolled out with the smoothness of a line that never gets the chance to go rusty.

I smiled politely. "So tell me about IVF," I said. "For a start, what kind of technology do you need to make it work?"

"It's all very low tech, I'm afraid," he replied, his mouth turning down at the corners. "No million-pound scanners or radioactive isotopes. The main thing you need is what's called a Class II containment lab, which you need to keep the bugs out. Clean ducted air, laminar flow, temperature stages that keep things at body tem¬perature, an incubator, culture media. The only really specialized stuff is the glassware-micro-pipettes and micro-manipulating equipment and of course a micro¬scope. Also, when you're collecting the eggs, you need a transvaginal ultrasound scanner, which gives you a pic¬ture of the ovary."

He was off and running. All I needed to do was provide the odd prompt. I was glad I wasn't his partner; I could just imagine how erotic his bedroom conversation would be. "So what are the mechanics of carrying out an IVF procedure?" I asked.

"Okay. Normally, women release one egg a month. But our patients are put on a course of drugs which gives us an optimum month when they'll produce five or six eggs. The eggs are in individual sacs we call follicles. You pass a very fine needle through the top of the vagina and punc¬ture each follicle in turn and draw out the contents, which is about a teaspoonful of fluid. The egg is floating within that. You stick the fluid on the heated stage of the micro¬scope, find the egg, and strip off some of the surrounding cells, which makes it easier to fertilize. Then you put it in an individual glass Petri dish with a squirt of sperm and culture medium made of salts and sugars and amino acids-the kind of soup that would normally be around in the body to nourish an embryo. Then you leave them overnight in a warm dark incubator and hope they'll do what opposite genders usually do in warm dark places at night." He grinned. "It's very straightforward."

The food arrived and we both attacked. "But it doesn't always work, does it?" I asked. "Sometimes they don't do what comes naturally, do they?"

"That's right. Some sperm are lazy. They don't swim well and they give up the ghost before they've made it through to the nucleus of the egg. For quite a few years, when we were dealing with men with lazy sperm, there wasn't a lot we could do and we mostly ended up having to use donor sperm. But that wasn't very satisfactory because most men couldn't get over the feeling that the baby was a cuckoo in the nest." He gave a smile that was meant to be self-deprecating but failed. Try as he might, you didn't have to go far below the surface before Old Man reasserted itself.

"So what do you do now?" I asked.

But he wasn't to be diverted. He'd started so he was going to finish. "First they developed a technique where they made a slit in the 'shell' of the harvested egg," he said, waggling his fingers on either side of his head to indicate he was using inverted commas because he was unable to use technical terms to a mere mortal. "That made it easier. Twenty-five percent success rate. But it wasn't enough for some real dead-leg sperm. So they came up with SUZI." He paused expectantly. I raised my eyebrows in a question. It wasn't enough. Clearly I was supposed to ask who Suzie was.

Disappointed, he carried on regardless as the impassive waiter delivered our main courses. "That involves passing a very fine micro-needle through the 'shell' and deposit-ing two or three sperm inside, in what you could call the egg white if you were comparing it to a bird's egg. And still some sperm just won't make the trip to the nucleus of the egg. Twenty-two percent success rate is the best we've managed so far. So now, clinics like ours out on the leading edge have started to use a procedure called ICSI."

"ICSI?" I thought I'd better play this time. Even pup¬pies need a bit of encouragement.

"Intracytoplasmic Sperm Injection," he said porten¬tously. "One step beyond."

I wished I hadn't bothered. "Translation?"

"You take a single sperm and strip away its tail and all the surrounding jelly until you're left with the nucleus. Then the embryologist takes a needle about a tenth the thickness of a human hair and pushes that through the 'shell,' through the equivalent of the egg white right into the very nucleus of the egg itself, the 'yolk.' Then the nucleus of the sperm is injected into the heart of the egg-"

"Wow," I said. It seemed to be what was expected. "So is it you, the doctor, who does all this fiddling around?"

He smiled indulgently. "No, no, the micro-manipulation is done by the embryologist. My job is to harvest the eggs and then to transfer the resulting embryo into the waiting mother. Of course, we keep a close eye on what the embryologist does, but they're essentially glorified lab technicians. I've no doubt I could do what they do in a pinch. God knows, I've watched them often enough. See one, do one, teach one." It's hard to preen yourself while you're scoffing curry, but he managed.

"So, does the lab have to be on twenty-four-hour standby so you're ready to roll the minute a woman ovulates?" I'd been presuming that Sarah Blackstone did her fiddling with eggs and microscopes in the watches of the night when the place was deserted, but I needed to check that hypothesis.

"We don't just leave it to chance," Gus protested. "We control the very hour of ovulation with drugs. But big labs like ours do offer seven days a week, round the clock service so we can fit in with the lives of our patients. There's always a full team on call; embryologist, doctor, and nurse."

"But not constantly in the lab?" "No, in the hospital. With their pagers." "So anybody could walk into the lab in the middle of the night and wreak havoc?" I asked.

He frowned. "What kind of article are you researching here? Are you trying to terrify people?"

Furious with myself for forgetting I wasn't supposed to be a hard-nosed detective, I gave him a high-watt smile. "I'm sorry, I get carried away. I read too much detective fiction. I'm sure people's embryos are as safe as houses." And we all know how safe that is in 19905 Britain.

"You're right. The lab's always locked, even when we're working inside. No one gets in without the right combi¬nation." His smile was the smug one of those who never consider the enemy within.

"I suppose you have to be careful because you've got to account to the Human Fertilization and Embryology Authority," I said.

"You're not kidding. Every treatment cycle we do has to be documented and reported to the HFEA. Screw up your paperwork and you can lose your license. This whole area of IVF and embryo experimentation is such a hot potato with the God squad and the politically para¬noid that we all have to be squeaky clean. Even the faintest suggestion that we were doing any research that was outside the scope of our license could have us shut down temporarily while our lords and masters investi¬gated. And it's not just losing the clinic license that's the only danger. If you did mess around doing unauthorized stuff with the embryos that we don't transfer, you'd be looking at being struck off and never practicing medicine again. Not to mention facing criminal charges."

I tore off another lump of nan bread and scooped up a tender lump of lamb, desperately trying not to react to his words. "That must put quite a bit of pressure on your team, if you're always having to look over your shoulder at what the others are doing," I said.

Gus gave me a patronizing smile. "Not really. The kind of people employed in units like ours aren't mad sci¬entists, you know. They're responsible medical profes¬sionals who care abut helping people fulfill their destiny. No Dr. Frankensteins in our labs."

I don't know how I kept my curry down. Probably the thought of being tended by the responsible medical pro¬fessional opposite me. Either that or the fact that I wasn't paying much attention on account of the fact that I was still getting my head around what he'd said just before. If I was short of a motive for terminating Dr. Sarah Black-stone, Gus Walters had just handed me one on a plate.