I didn't care whether the monologue about a renaissant Nazi group was genuine or not. Given Zossen I needed no further blandishments. They'd wasted my time.

The cramp was beginning so I crawled on my hands and knees to the back of the box and got into the chair as if I'd just come in again after the interval. Pol did the same, brushing his hands carefully across the knees of his trousers. I sat with my eyes shut, thinking.

Now that I'd stopped resenting him and made the decision I could admit that it was my own fault. For years I'd operated in strict hush, as I'd been trained to do; so when they seconded me to liaise with the Federal Z Commission and supply the Hanover Tribunal with bodies for trial, I didn't see much point in coming into the open air. If I had, my face would have become, in those six months, the most recognisable feature ever to have spanned the crossed hairs of a telescopic rifle-sight. That wouldn't have worried me because I'd moved between Berlin and Hanover and back with a constant cover of six men, like a pocket president. But my insistence on secrecy had got me on this hook. After six months I knew Berlin like my face, yet my face was unknown in Berlin.

No wonder they'd come for me.

For a while Pol must have thought I'd refuse. Then he knew it was going to be all right, and had put the briefcase on my knees. It would contain all the information they could give me, all the names, suspects, dossiers, leads and theories they could cull from the whole of the Bureau files, a complete and exhaustive breakdown on the field. But they'd come for me because I knew even more.

"Pol," I said.

He was sitting with his arms folded, head tilted, watching the show. His head tilted the other way, towards me.

I said: "Tell them not to try tapping my phone again. I want to be able to know that if I hear any clicks, it's the adverse party doing it."

"Very well."

"No cover."

"Noted."

"Communication Post and Bourse."

"Available."

When the stage began filling and the music was loud I asked him for his photo and he gave it to me. The zip on the briefcase was the interlocking plastic flange type and opened silently. Inside was the folder with the black cover. It was the memorandum. Between the typed lines was written, invisibly, my future. In detail it gave specific outline to the manner of my life. It made no mention of the possible manner of my death. It was thus a highly personal document, and on the cover was a single letter: Q.

I put the photograph in and shut the case.

The snow had stopped. It had been packed into ice by the tyres, and the traffic was slow and quiet. Half-way along the Kurfursten-strasse a street bollard lay smashed and they ere towing the car clear; rusty water steamed as it poured from the radiator.

Above the roofs the sky was black and the stars close. It was easy to see tonight that the earth was a star too, adrift in a void; a fur collar gave little protection against the thought.

I had left the box a minute before Pol so that when he went down the main staircase in the throng he couldn't see me. I had kept back by the wall on the balcony to get a good look at his face in the mirror above the stairs. I compared it with his photograph and asked for a plain envelope on my way past the box-office. In the street I put the photograph inside and addressed it to Radio Eurosound, posting it, unstamped, in the box at the kerbside.

It was fifteen minute's walk to my hotel on dry pavements. Tonight it took just short of thirty. The ice crackled underfoot. Only four of my cover men were within sight, picking me up at the Neukomodietheater and tailing at a distance. They worked well but they were useless because the system was useless. Once inside a theatre you were meant to be safe, but Pol could have easily been one of the adverse party and could have slipped a knife into me and no one the wiser. Useless.

There were fresh placards along the Bulow-strasse and I saw Peters's name, and bought a late edition. Ewald Peters, Chancellor Erhard's chief personal security man. Only last month he'd been in London, protection for the Chancellor in case anyone threw a tomato. Now they'd arrested him. Charge: mass murder of Jews. He was a senior official in the Federal Kriminalpoliiei and responsible for the security of the Chancellor, the President of the Republic, and visiting statesmen in Bonn. How much had Erhard known? Nothing. He'd resisted pressure recently at the Party Congress, insisting on continuing the trials and refusing the plea for an amnesty that would release a score of Nazis from the cells. If he'd suspected his chief bodyguard he'd have turned the man over right away.

It was the Z Commission who'd nabbed Peters. I admired them for that – they were more bulldog than dachshund. There was already a lot of unrest inside the department, because their job was exclusively to hunt down the Nazi remnant, and since there were several Nazis in the hierarchy of their own section they risked losing promotion with every arrest they made. A very odd way to run an eisenbahn.

Yesterday they'd got Hans Krueger, West German Minister for Refugees. Charge: serving as a judge at a ‘special’ Nazi court in Poland. In a few days' time there'd be a new name on the placards, because the Z-Polizei were just now tying up the loose ends. Franz Rohm, Secretary of the Road Safety Committee. It had taken me three weeks to find him. I was pleased with that one because suicide was among my subjects and I knew Rohm would kick a chair from under him any day now. I didn't hold with capital punishment; it had been abolished in West Germany since 1949, and that was good; but these men were infectious and there was one thing worse than that they should hang it was that they should live, and infect others.

The snow crackled under my feet.

I turned into the north end of the Kreuzberg Garten and passed the fountain; it was a frozen ice-cake. Another dozen yards and there was some shadow cast by shrubs, and I melted, waiting. When the first one came past I moved into the light of the lamps and stopped him, saying in German:

"For local Control, please. I've met Pol. Spelt P-O-L. From now on they're to call off all cover, fully urgent. They can find me Post and Bourse."

He lit the cigarette I'd put between my lips.

"I shall have to confirm before I leave."

"The sooner the better," I said. "The others can stay until you've confirmed. Then call them off. I want a clear field from midnight."

I thanked him for the light and walked on, flicking the cigarette away as soon as there was a chance. Nearing the hotel through the Schonerlinde-strasse where the pavement was being cleared of snow I heard an airliner go surging up from Tempelhof less than a mile away, and turned to watch its lights.

In the morning I would have to cancel my reservation on Lufthansa 174, because it was written between the lines of the thrice-accursed memorandum that I must stay.

Naumann: the snowman. Sickert: sick at heart. Kalt: cold. Helldorf: held off. Kielmann: kill a man. Hansnig: hands. Edsel: easily.

Shuffle.

Helldorf. Sickert. Kalt. Naumann. Kielmann. Edsel. Hansnig.

Try it.

I held off, sick at heart to see the cold snowman kill a man so easily with his hands.

There were forty-odd names on a single sheet of the memorandum, each one a possible contact of Heinrich Zossen. In half an hour they were locked in my memory and the sheet was added to the pile for burning. My habit was to travel light; by morning the complete memorandum would be cremated.

A mental note: keyword 'whale.' Tell Control to turn the heat off the big fish so that they relaxed their vigilance while I got within range.