Two untapped sources of information were mine for the taking but I wasn't going to take them. Solly Rothstein's sealed container was one. Unless I were missing something, that container held all the vital information that he'd tried to bring me when they'd shot him down. It would lead me right to the Phoenix base. I wanted to get there without trading on the death of a friend I'd helped to kill. Inga was the other untapped source. She was a defector of long standing but I would not trade on our innocent afternoon and ask her to give me all the information she had at the time of her defection. (This was how she would see things, and I must play it her way.)

The single route to their base was open to me: the tag who was behind me now must be made to lead me there. It was almost the only justification for a switch.

By nine o'clock I had managed to check him visually twice. He was a new man and less efficient than the one I'd flushed last night. Forty-five minutes later I flushed him outside Kempinski's in the Kurfurstendamm, though clumsily. (He nearly got run over crossing the zebra on the red.) We spent half an hour dodging about and then he went into a phone-kiosk to report on the situation. His orders became obvious within ten minutes: he took a taxi and I followed him in mine, all the way back to the Hotel Zentral in Mariendorf. He had lost me, hadn't a hope of picking me up again by chance, and had been ordered back to our starting-point, the only known place where I could be found.

We were both annoyed. The morning was wasted. I had borne it in mind, when launching my damp-squib offensive, that he wouldn't necessarily lead me to his own base after I did the switch. It had been hope, not expectancy, that had started me off. There had been no other way of trying to get near their base again.

But tagging is like driving: an experienced operator does it automatically, and can think about other things while he's doing it. I had thought a lot about Solly Rothstein between Mariendorf and the Kurfurstendamm and back, and it had been brain-think. Before, it had been stomach-think, emotional thinking. Guilty because of his death, I'd let myself believe that to use the information inside that container would be to trade on tragedy, to exploit Solly for my own purposes. But my purposes were his. If I could kill off Phoenix, a Nazi organisation, it would avenge the murder of his wife; and Solly had lived for that and died for it.

I phoned Captain Stettner at the Z-Bureau. He said:

"I've been trying to make contact with you. I didn't know where you'd moved."

There was no audible sign of line-tap but we didn't have to take chances so I just told him I would go to his office within the hour.

Sleet had started so I used the BMW, not even checking the mirror. They knew I was linked with the Z-polizei. already. On the way I thought about Kenneth Lindsay Jones because the question of the Grunewald See had been coming up at me again, on and off. I thought I'd answered it: Oktober had told them to drop my corpse into the Grunewald because he knew I was listening and would be convinced that they were genuine orders to kill, since that was where KLJ was dumped. That answer might be correct but now I suspected it, simply because it kept on calling for my attention. It would have to be dealt with.

The only clue might lie in KLJ's last report to Control before he died. The information in that report was already filed in my head, taken from the burned memorandum; but I had never seen the report itself. If KLJ had had any premonition of his death it would be there in the phrasing of his report, and the memorandum didn't quote reports verbatim. It carried edited information only.

I signalled Control before reaching the Z-Bureau, using a letter-card. REQUEST EARLY SIGHT OF LAST KLJ REPORT IN ORIGINAL FORM. HOTEL ZENTRAL MARIENDORF.

Captain Stettner was alone in his office and greeted me with slight embarrassment. He was a man typical of his stock, with a strong face and clear unimaginative eyes. Let him follow a saint and he would do saintly things; put him to work with a devil and he would out-foul Satan. They are born to obey, these men, born to be led, and it's luck that elects their leader. Stettner was young, perhaps thirty, and so he was working for a liberal chancellor; it was his duty to bring in the henchmen of a long-dead maniac and to hand them to justice. Had he been fifteen years older he would have graduated from the Hitler Youth in 1939 to command an SS company pledged to genocide in the glorious name of the Fuhrer.

He said to me: "You are not sleeping well, Herr Quiller."

"I haven't the time." It wasn't lack of sleep that was showing in my face, but the strain of Oktober's succession of treatments. It irked me that it showed. "You said you were trying to contact me?"

"Yes. I'm sorry you didn't feel it necessary to give me your change of address."

"I didn't know you'd need my help."

His embarrassed air increased. "I assume our relationship to be one of mutual assistance."

No answer. I studied the clearness of his skin and the freshness of his eyes and wished I were thirty, so that whatever I went through it didn't show in my face.

"I believe you knew Dr. Solomon Rothstein well?" he asked me suddenly.

"I knew him a long time ago."

"In the war?"

"Yes."

"Would you tell me what kind of work he was doing, in the war?"

I said: "In what precise way can I mutually assist you, Herr Stettner?"

"Of course you are not obliged to answer my questions, Herr Quiller -"

"That's right. You talk and I'll listen."

He considered this and I could see the brightly-polished cogs going round inside his transparent plastic skull. He worked for the Federal Government. I worked for an intelligence service of an Occupying Power, and was therefore of a technically higher status. Therefore I called the tune. When he got it set out correctly he followed procedure and said unemotionally:

"We have been trying to break a cipher and we have so far failed. I hoped you might succeed, since you once worked with Dr. Rothstein and might remember any cipher systems he used."

I knew what had happened.

"We can't trace his brother in Argentina – Isaac Rothstein. We have now opened the canister that was found in the laboratory on the Potsdamer-strasse, after checking it for explosive with magnetic sounding. It contains a glass phial and a sheet of paper covered with cipher."

It was some time since I'd had a piece of luck. I had expected a lot of trouble in persuading them to open the container and even more trouble in persuading them to show me what was inside.

I said: "I'll have a go."

He tried not to look relieved. "We are keeping the original, and will give you an exact copy. It's unnecessary to warn you that it must not be let out of your close possession."

"I thought of offering the publication rights to Der Spiegel."

He span in his chair. "But that would be unthinkable, Herr Quiller! Surely you must realise that the very highest possible secrecy has to be… maintained…" and the wind went out of him slowly while I watched him. A wan smile came to his face. "Of course… a little joke. Of course."

He took time to recover. I asked him: "Are you thinking of opening the glass phial?"

"My superiors believe it might be very dangerous to do that. Dr. Rothstein's main work was carried out in a special laboratory behind the one that was raided, and it is sealed off with decontamination air-locks. One of his staff has been interrogated and has warned us that Dr. Rothstein was researching on certain strains of bacteria highly dangerous to man. Unless the ciphered material specifies any good reason for our opening the glass phial it will probably be put into a furnace, still sealed. "He gave me a plain grey envelope. "This is your copy, Herr Quiller. May I wish you success."