But the ring of trees was so quiet, a ring of tombstones.

I said: "All I want is the report. Then stop getting in my way."

I walked back to the BMW and sat inside. He leaned through the window so that his body covered it, and dropped the envelope on to the seat beside me. His face was dark in the gloom of the interior.

"Never forget," he said, "that the whole of our organisation is behind you, at every minute."

"Just keep it clear of me."

I read the last testament. The writing was thin and hurried.

Dec. 3. Tags now a nuisance, time wasted in flushing. But have got a line on base, will confirm soon. Things very tricky now, request no contacts any account. May not receive Bourse. May not signal for a time. KLJ.

The restaurant was full and I sat working on the report, fiddling with an underdone lump of schweinefleisch.

So he had reached much the same stage as I had reached now, and had told them – as I had told Pol an hour ago – keep clear of me. Then he had gone in, right the way in, and couldn't be allowed to live.

A line on base. What line? It didn't matter. He had followed it and they had killed him off because he was too close. So here was the address of the Phoenix base. I had been there myself without being allowed to know where it was. Now I knew where it was.

I put the slip of paper back into the envelope, which was already addressed to Eurosound. The man brought my bill and I paid it, going to the lavatory and using a penknife to ease out the Rothstein document. There was a postbox at the intersection not far from the restaurant and I sent off the report as promised. One quick turn round the block showed there was no foot-tag, but I had been followed to the restaurant by the small grey NSU, because I had called at the Zentral after leaving Pol and they'd picked me up from there. It was parked five cars behind my BMW. I didn't want to waste time flushing him and I didn't want to risk being snatched with the document on me. There was a polizei officer on duty at the intersection so I crossed over and showed him the Z-Commission ausweis that Captain Stettner had given me: it was no more than a laisser passer into the Z-Bureau back-room departments but it would probably do.

I said: "I've reason to believe that there's a man in a stolen car across the road. The NSU number BN.LM.11 outside the friseur. You may care to check it."

We walked together to the other side and I hung back as we passed my BMW. He didn't miss me because he was sizing-up the NSU as he approached it, and as I drove away I saw him in the mirror, checking the driver's papers.

It took half an hour to change the BMW at the Hertz office but it would have taken longer than that to flush the tag and I had now altered the image. I couldn't risk being picked up by sheer chance from now on, because I had the document on me and because, as KLJ had put it, things were very tricky now.

A million lives, Pol had said. And mine. A million and one. Because I was going to survive. The man in London wasn't going to light another cigarette and send for a replacement.

I had never whistled in the dark before and the tune came thinly.

The new image was a very fast 230SL pagoda-top Mercedes with fuel-injection, the last thing they would look for, and I took it right out west to the edge of the Havel and parked on the Schildhorn peninsula. Mist shrouded the waterscape and the light was grey. The monument poked its sandstone finger at the sky and I didn't look at it more than once because everything reminded me of cemeteries.

Treble-combination frequencies in English and German ING-ENT-SCH-EUN. Check and assume, recheck. No go.

Two hours by the black-and-gold clock on the facia, cramp in the legs.

Reverse and read backwards, add prefix and suffix nulls LKAOEI – JUQOP – AJSHGFRWEQT. Pick a new set and stay clear of the multisyllabics, obviously Latin for bugs.

Four hours and the circulation seizing-up.

A walk by the beautiful waterside, dead land and dead water, a mezzotint laced with the sombre dark of the pines, a place for lost souls and ferrets, with the sirensong crying softly across the mirrored sky. AJSHGFRWEQT! they sang, OQUISTRI!

The only living thing I saw the whole afternoon was a dog that came from the mist and pissed at the foot of the monument and vanished as it had come.

Patience.

Possible key: U=S, B=M, O=A, eight others. Pick a long one for pride's sake: VASOSFGWOBU. Gave OTNANGILAMS. Reverse and add prefix and suffix nulls. Gave SMALIGNANTO.

Nearly missed it because it sounded Spanish.

Drop prefix and suffix nulls. MALIGNANT.

Check another. Thought we had Sprit, German for Alcohol, yesterday. But hope has a grasshopper leap. RCIMEDIPEF. Drop nulls and reverse: EPIDEMIC. Come in, Solly, come in…

18 : OBJECT 73

The hands of Captain Stettner had begun shaking.

I sat facing him, trying to think, but gave it up. The room was so filled with his horror that detached thought was impossible. He picked up a telephone long before he had finished reading my deciphered version of the Rothstein document.

"Fifteen," he said to the switchboard.

That would be their forensic laboratory, the safest place for keeping a glass phial whose contents might be dangerous.

"Captain Stettner," he said, his voice only just under control. "You have an object numbered 73 in your keeping. Have you received any orders to open it?" He went on staring at me, and I remembered his uneasiness when the bogus doctor from Phoenix had come to this office to inject him. "Then if you receive any such order, refer to me first, immediately. I have information that the contents are highly dangerous. Please take all steps to ensure that it remains sealed and locked away. Accidental breakage could cause a whole-scale disaster."

He went on a bit more about this, and there was a mist of sweat on the receiver when he put it down. Then I had to wait while he finished reading the decipherment. The single sheet of paper went on quivering in his hands.

"I don't know," he said at last, "anything about these matters. Anything about this bacillus. Do you?" He was like a child pleading to be comforted, to be told that it wasn't really dark, only night-time.

"Not much," I said.

He was running the back of his hand round his face. "I mean," he asked without hope, "is it possible that Dr. Rothstein was deranged in some way?"

"In a world as mad as this, how do we define derangement?"

No comfort in that. He tried again. "This – this talk of a plague. Could one small phial cause such a thing?"

I wished he'd straighten up so that I could sound him on the general background of Solly's operations. Perhaps it would be quicker in the long run to tell him the worst and then put a few questions of the kind that interested me more.

"Yes, a phial that size could do it. At this moment, America, Russia, England, France, Japan and China – there are probably others – are researching on botulinus toxin, culturing it and killing it to provide the basis for an antidote. Eight ounces of it could wipe out the world population. We all need the antidote, just as we all need the best anti-missile missile, to make sure we can go on living in brotherly love. It may be that Rothstein was also working on that toxin, but it isn't what he put into the phial. That's just one of the plague-group."

A telephone began ringing and he cut the switch, so I carried on. "There are three forms of plague. The classic bubonic type causes the superficial lymph-glands to swell and suppurate into dark abcesses. Type two, the septicaemic, poisons the blood. Type three affects the lung. It's even more infectious than the bubonic, which killed off a quarter of the population of Europe in the fourteenth century – the English called it the Black Death. This third type is the pneumonic. Dr. Rothstein gives it the more correct name in that document: pastorella pestis. It's a rod-shaped bacillus that can be grown in a laboratory on suitable culture medium. Once it gets loose, infection is by exhaled droplets and the incubation period is a short one three or four days. Three times quicker than smallpox."