'Very well, then. The virulent strain was removed from the pigeons and subcultured onto blood agar plates.' He broke off, looking at the blankness of my ignorance. 'Let me put it this way. The live virulent germs were transferred from the pigeons onto dishes containing blood, where they then multiplied, thus producing a useful quant.i.ty for injecting into the serum horses.'

'That's fine,' I said. 'I do understand.'

'All right.' He nodded. 'Now the blood on the dishes was bull's blood. Bovine blood.'

'Yes,' I said.

'But owing to someone's stupid carelessness, the blood agar plates were prepared one day with horse blood. This produced a mutant strain of the disease.' He paused. 'Mutants are changes which occur suddenly and for no apparent reason throughout nature.'

'Yes,' I said again.

'No one realised what had happened,' he said. 'Until the mutant strain was injected into the serum horses and they all got erysipelas. The mutant strain proved remarkably constant. The incubation period was always 24-48 hours after inoculation, and endocarditis... that is, inflammation of the heart valves... was always the result.'

A youngish man in a white coat, unb.u.t.toned down the front, came into the room next door, and I watched him vaguely as he began pottering about.

'What became of this mutant strain?' I said. Livingston nibbled a good deal with the lips, but finally said, 'We would have kept some, I dare say, as a curiosity. But of course it would be weakened by now, and to restore it to full virulence, one would have to...'

'Yeah,' I said. 'Pa.s.s it through pigeons.'

He didn't think it was funny. 'Quite so,' he said.

'And all this pa.s.sing through pigeons and subculture on agar plates, how much skill does this take?'

He blinked. 'I could do it, of course.'

I couldn't. Any injections I'd handled had come in neat little ampules, packed in boxes. The man in the next room was opening cupboards, looking for something. I said, 'Would there be any of this mutant strain anywhere else in the world, besides here? I mean, did this laboratory send any of it out to anywhere else?'

The lips pursed themselves and the eyebrows went up. 'I've no idea,' he said. He looked through the gla.s.s and gestured towards the man in the next room. 'You could ask Barry Shummuck. He would know. Mutant strains are his speciality.'

He p.r.o.nounced 'Shummuck' to rhyme with 'hummock'.

I know the name, I thought. I... oh my G.o.d. The shock of it fizzed through my brain and left me half breathless. I knew someone too well whose real name was Shummuck.

I swallowed and felt shivery. 'Tell me more about your Mr Shummuck,' I said.

Livingston was a natural chatterer and saw no harm in it. He shrugged. 'He came up the hard way. Still talks like it. He used to have a terrible chip on his shoulder. The world owed him a living, that sort of thing. Shades of student demos. He's settled down recently. He's good at his job.'

'You don't care for him?' I said.

Livingston was startled. 'I didn't say that.'

He had, plainly, in his face and in his voice. I said only, 'What sort of accent?'

'Northern. I don't know exactly. What does it matter?'

Barry Shummuck looked like no one I knew. I said slowly, hesitantly, 'Do you know if he has... a brother?'

Livingston's face showed surprise. 'Yes, he has. Funny thing, he's a bookmaker.' He pondered. 'Some name like Terry. Not Terry... Trevor, that's it. They come here together sometimes, the two of them... thick as thieves.'

Barry Shummuck gave up his search and moved towards the door.

'Would you like to meet him?' Mr Livingston said.

Speechlessly, I shook my head. The last thing I wanted, in a building full of virulent germs which he knew how to handle and I didn't, was to be introduced to the brother of Trevor Deansgate.

Shummuck went through the door and into the gla.s.s-walled corridor, and turned in our direction.

Oh no, I thought.

He walked purposefully along and pushed open the door of the lab we were in. Head and shoulders leaned forward.

'Morning, Mr Livingston,' he said. 'Have you seen my box of transparencies, anywhere?'

The basic voice was the same, self-confident and slightly abrasive. Manchester accent, much stronger. I held my left arm out of sight half behind my back and willed him to go away.

'No,' said Mr Livingston, with just a shade of pleasure. 'But Barry, can you spare...' Livingston and I were standing in front of a work bench which held various empty gla.s.s jars and a row of clamps. I turned leftwards, with my arm still hidden, and clumsily, with my right hand, knocked over a clamp and two gla.s.s jars.

More clatter than breakage. Livingston gave a quick nibble of surprised annoyance, and righted the rolling jars. I gripped the clamp, which was metal and heavy, and would have to do.

I turned back towards the door.

The door was shutting. The backview of Barry Shummuck was striding away along the corridor, the front edges of his white coat flapping.

I let a shuddering breath out through my nose and carefully put the clamp back at the end of the row.

'He's gone,' Mr Livingston said. 'What a pity.'

I drove back to Newmarket, to the Equine Research Establishment and Ken Armadale.

I wondered how long it would take chatty Mr Livingston to tell Barry Shummuck of the visit of a man called Halley who wanted to know about a pig disease in horses.

I felt faintly, and continuously, sick.

'It's been made resistant to all ordinary antibiotics,' Ken said. 'A real neat little job.'

'How do you mean?'

'If any old antibiotic would kill it, you couldn't be sure the horse wouldn't be given a shot as soon as he had a temperature, and never develop the disease.'

I sighed. 'So how do they make it resistant?'

'Feed it tiny doses of antibiotic until it becomes immune.'

'All this is technically difficult, isn't it?'

'Yes, fairly.'

'Have you ever heard of Barry Shummuck?'