The closet was in the corridor, between his kitchen and his bedroom, a teeming hollow into which, over the years, he had emptied his life. Rising from his chair he went over and gave its closed door a speculative look. The last time he'd opened it was a few weeks ago, while searching for an old laptop: an avalanche of discarded objects had come tumbling off the shelves. He placed a hand on the knob and prised the door gently open. A tremor ran through the closet, but to his relief everything stayed in place.

He began to empty the shelves, one by one, piling up everything in the corridor: old shoes, timerless toasters, broken umbrellas, accordion files. And then he spotted it, hidden behind a pile of yellowing Arabic newspapers: a brown rectangular shape, wrapped in transparent plastic.

He took it down and carried it into his bedroom, leaving everything else piled in the corridor. Sitting on the edge of his bed, he unwrapped it, blowing off the dust. He rubbed his finger over the rectangle of clear plastic that covered the machine's microcassette and pushed the eject button. Somewhat to his surprise the mechanism seemed to be in working order. The cassette popped out and he cleaned it carefully, with the corner of his bedsheet.

Slipping the cassette back, he plugged the machine in.

The blinking light came on, and the cassette began to turn. And then, punctuated by squeaks from the cassette's dusty wheels, he heard a voice, blunted by the passage of time, but still more or less audible. He turned the volume up.

'Listen, you fucking creep,' said the voice, just as he remembered it, 'you think this stuff's all just a pie in the sky huh? You think I don't have any proof? Well let me tell you something: I don't know what they call proof down where you live but I've got something that's good enough for me.

'You remember I mentioned a guy called W. G. MacCallum – a doctor and research scientist who made one of the big breakthroughs in malaria in 1897? OK, listen to this: what this guy did was he showed that the little "rods" that Laveran had seen, coming out of the parasite's hyaline membrane, weren't flagellae, like the great man thought. In fact they were exactly what they look like – that is, spunk – and what they did was what spunk does, which is make babies. You wouldn't think it would take a Galileo to figure that out: I mean what did they look like, for Pete's sake? But the fact is, that MacCallum was the first to get it. He wasn't the first to see it, but he was the first to figure it out. Laveran saw it before him, but he didn't get it: guess Lav-the-Man didn't exactly have sex on his mind. Ronnie Ross saw it about a year before MacCallum did and he thought he'd seen his father. No kidding; he thought the flagella was a kind of soldier, going out to war, like Pa Ross on his white horse. I mean, think about it: Ronnie sees this thing that looks like a prick; it goes swimming across his slide and starts humping an egg, and what does Ronnie make of it? He thinks it's the charge of the Light Brigade. The moral is: just because you take a boy out of Victoria 's England, doesn't mean you've got her out of the boy.'

Here there was a beep and the voice was cut abruptly short. A moment later it resumed: 'It's me again, your pal Morgan, your dumbass machine cut me off. Now, where was I? Oh yeah, MacCallum.

'Anyway, MacCallum was just a kid, and a Yank, stuffed full of pumping red-blooded hormones, and he knew what he'd seen all right. He wrote a paper fast as he could and presented it at a big doctors' convention in Toronto in 1897. It went down so well that he got to go jogging with Mr Germicide himself, Lord Lister.

'OK, so MacCallum was the first to figure it out. But back when he was getting started on his research, he worked with a whole team down at Johns Hopkins in Baltimore. The other members of the team were Eugene L. Opie and a guy called Elijah Monroe Farley. MacCallum and Opie were the heavies, while Farley was kind of like the water-boy and gofer. He didn't last long. Just when the team was getting started on malaria, Farley got the itch to see the world. He volunteered his services to a missionary group from Boston, and next thing anyone knew he'd shipped out for India.'

Here there was another interruption. With an aggrieved comment, Murugan's voice resumed:

'OK, so you want to know how I know all this? It happened like this: a couple of years ago I was looking through Eugene L. Opie's private papers in Baltimore. I was checking out his lab notes, and what do you think fell out? A letter from Dr Elijah Monroe Farley addressed to Opie. It was like it had been left there to wait for me. Farley wrote the letter after visiting a lab in Calcutta – a lab run by a guy called D. D. Cunningham. That was the lab where Ross ran the last lap of his race, in 1898. D. D. Cunningham was his predecessor at the lab, and Ross didn't get there until early 1898. But this letter was written in 1894 and it was the last thing Elijah Farley ever wrote.

'To cut to the chase: you know what was in this letter? Well there was a lot of stuff – I mean like pages and pages of stuff – but buried under all the garbage there was this sentence that proves that Farley had already found out about the role of the so-called "flagellae" in sexual reproduction, long before MacCallum. That is, he already knew what MacCallum hadn't yet discovered. And when I worked out the dates and stuff, it was clear that the only place he could have learnt it was in Calcutta. But who could he have learnt it from? D. D. Cunningham didn't know and didn't care and at this time Ronnie Ross was still in the research equivalent of Montessori school. Fact is, Ronnie never managed to work out the stuff about the flagellae for himself: just couldn't bring himself to deal with all that sex happening under his 'scope. He only found out in 1898, when Doc Manson mailed him a summary of MacCallum's findings.

'And that's not all. Remember Ross's assistant – Lutchman or Laakhan or whatever you want to call him? Well, I have a hunch Farley met him long before Ross did: in fact Farley may have seen too much of him for his own good.

'The trouble is, Farley's letter was uncatalogued, and I only saw it that one time. I put it back, and filled out a form asking for permission to xerox it. But it wasn't there the next time I looked. The librarian wouldn't believe me, because it wasn't on the catalogues. I've never been able to find it again, so strictly speaking I still don't have my smoking gun. But I saw it and I held it in my hands and when I got back to my motel that day I wrote it up, as I remembered it. And guess what? You can have a preview: if you look at your monitor, you'll see there's a document waiting for you right this minute, in your mail-folder…'

MURUGAN ARRIVED at the guest house to find Mrs Aratounian watching TV and drinking pale-yellow gimlets.

'Why, there you are, Mr Morgan,' she said, patting her fraying, antimacassared sofa. 'Do sit down. I was just beginning to worry about you. Can I pour you a gimlet? Are you sure? Just a chota – a tiny nightcap to bring you sweet dreams?'

Mrs Aratounian had discarded the blue velvet dressing gown she was wearing in the morning, when Murugan arrived; now she was dressed in a white blouse and severe black skirt. Bottles of Omar Khayyam Dry Gin and Rose's Lime Cordial stood on a small carved table beside her, barely visible amongst clumps of leaves, growing out of ornate brass planters.

She followed Murugan's eyes anxiously as his gaze strayed to the table. 'No?' she said, squinting at him over her bifocals. 'You don't like Omar Khayyam? I've got a bottle of Blue Riband gin somewhere; just for special occasions. I could go and look for it: I know it's here somewhere.'