Len Deighton - Spy Hook

Here on the canal bank is the building where Admiral Canaris, Hitler's chief of military intelligence, sat in his office plotting against his master. And into these murky waters the battered body of Rosa Luxemburg was thrown by the army's assassins.

Soon the dark tree-lined canal was left behind and the taxi was in Kreuzberg, speeding past Leuschner's Café and along Koch Strasse – Berlin 's Fleet Street – and to the Friedrichstrasse intersection that provides a view into the heart of East Berlin.

I paid off the cab and made a point of asking the American soldier on duty in the temporary hut, which has been positioned there for forty years, what time the checkpoint closed. It never closed, he told me; never! It was enough to make sure he remembered me passing through. If I was going to leave a trail that the MPs would follow, it would be better to make it wide and deep. The Department would not be fooled, but on past performance it would take a little time to get them into action. A Friday evening: Dicky Cruyer would have to be got back to his office from somewhere where the fishing and shooting was good and the telephoning demonstrably bad.

On the Western side of Checkpoint Charlie you'll find only a couple of well laid-back GIs lounging in a hut, but the Eastern side is crowded with gun-toting men in uniforms deliberately designed in the pattern of the old Prussian armies. I gave my passport to the surly DDR frontier guard who showed it to his senior officer who pushed it through the slot under the glass window. There it was photographed and put under the lights to find any secret marks that previous DDR frontier police might have put there. They gripped my passport with that proprietorial manner that all bureaucrats adopt towards identity papers. For men who man frontiers regard passports and manifests as communications to them from other bureaucrats in other lands. The bearers of such paper are no more than lowly messengers.

As a thinly disguised tax, all visitors are made to exchange Western money for DDR currency at an exorbitant rate. I paid. Guards came and went. Tourists formed a line. Buses and private cars crawled through and were examined underneath with the aid of large wheeled mirrors. A shiny new black Mercedes, flying the flag of some remote and impoverished African nation, was halted at the barrier behind a US army jeep that was demonstrating the victorious armies' right to patrol both sides of the city. The DDR guards did everything with a studied slowness. It all takes time: here everything takes time. And some of the victors have to be kept in their place.

East Berlin is virtually the only place to find a regime staunch and wholehearted in its application of the teachings of Karl Marx. Why not? Who could have doubted that the Germans, who had given such unquestioning faith and loyalty – not to mention countless million lives – to Kaiser Wilhelm and Adolf Hitler, would soldier on, long after Marxism had perished at its own hand and been relegated to the levelled Führerbunker of history.

The taller buildings around the shanty-town of huts that is Checkpoint Charlie give the feeling of being in an arena. So do the banners and the slogans. But the bellicose themes have gone. It is a time of retrenchment. The communist propaganda has abandoned the promises of outstripping the West in prosperity or converting it politically. Now the messages stress continuity and security and tell the proletariat to be grateful.

Emerging from Checkpoint Charlie you can see all the way to Friedrichstrasse station. There, a steel bridge crossing the street cuts a pattern in the indigo sky. Across the bridge go the trains that connect Paris with Warsaw and eventually Moscow, but the bridge itself is also the Friedrichstrasse station platform of the elevated S-Bahn, the commuter line that runs through both East and West Berlin.

The sight of the bridge gives the impression that the station is only a short walk, but the distance is deceptive and as I walked up Friedrichstrasse – past the blackened and pockmarked shells of bombed buildings that people said were owned by mysterious Swiss companies that even the DDR did not wish to offend – I remembered too late that it's worth getting a cab that short distance when one is in a hurry.

The S-Bahn station Friedrichstrasse provides another demonstration of the enormous workforce that the DDR devotes to manning the Wall. I went through its agonizingly slow passport control – there are even more checks on people leaving than on those entering – and eventually went through the tunnel and up to the platform.

The station is a huge open-ended hangar-like building with overhead gantries patrolled by guards brandishing machine guns. The S-Bahn's rolling stock, like the stations and the track, are ancient and dilapidated. The train came rattling in, its windows dirty and the lights dim. I got in. It was almost empty: those privileged few permitted to cross the border are not to be found travelling westwards at this time of evening. It took only a few minutes to clatter over the Wall. The 'anti-fascist protection barrier' is particularly deep and formidable here where the railway crosses the Alexander Ufer: perhaps the sight of it is intended to be a deterrent.

There is an almost audible sigh of relief from the passengers who alight at Zoo Station. I had to change trains for Grunewald, but there was only a minute or two to wait and it was quicker than taking a cab and getting tangled up in the Ku-Damm traffic which would be thick at this time.

From the station I walked to Frank Harrington's home. I approached it carefully in case there was anyone waiting for me. It seemed unlikely. The standard procedure was to cover the frontier crossing points-those for German nationals as well as the ones for foreigners – and the airport. On a Friday night at short notice that would provide more than enough problems. Frank as the Berlin chief was already given special protection by the civil police. My guess was that whoever was allotting the personnel would decide that Frank couldn't be afforded a car and a three-shift watch. They would describe me as a fugitive special category three: 'possibly armed but not dangerous'.

It was Axel Mauser – one of the kids at school here – who first showed me the proper way to climb drainpipes. Until then I'd been using my hands and getting my clothes into a terrible state. It was Axel who said, 'Climb ropes with your hands; drainpipes with your feet' and showed me how the burglars did it without getting their hands dirty. I don't know who showed Axel how to do it: his father probably. His father, Rolf Mauser, used to work in the hotel for Lisl. Rolf Mauser was an unscrupulous old crook. I'd believe almost anything of Rolf.

I was remembering all that as I climbed into the upstairs master bedroom of Frank's big house in Grunewald. There were no burglar alarms at the back. I knew where all the burglar alarms were. I'd helped Frank decide where to put them. And Frank always kept the bathroom window ajar. Frank was a fresh-air fiend. He'd often told me it was unhealthy to close the bedroom windows no matter how cold it was. Sometimes I think that's why his wife doesn't like living with him; she can't stand those freezing cold bedrooms. I told Fiona that once: she said don't be ridiculous but it didn't seem ridiculous to me. I can't stand cold bedrooms: I prefer unhealthy warmth.

Frank wasn't in bed of course, I knew he wouldn't be. That's why I got in upstairs. I got through the window and then had to stand there, carefully removing from the sill about three hundred bottles, tubes and sprays of bath oil, shaving soap, hair shampoo, toothpaste and God knows what. What could Frank ever want with all that stuff? Or was it the unredeemed property of Frank's girl-friends?

Finally I made a foot space on the window sill and from there I could step down into the bath and…Jesus, there was water in the bath. Lots of water! What did that bloody Tarrant do if he couldn't even make sure the bath was drained properly? My shoe was full of soapy water. How disgusting! I didn't like Frank's valet and the feeling was mutual. I suppose, if I was to examine my feelings closely, the principal reason I didn't just knock on Frank's front door was because I wouldn't trust that bloody man Tarrant as far as I could throw him. In a jam like the one I was now in, I would give Tarrant just three minutes before catching sight of me and getting on the blower and reporting me. Less than three minutes: thirty seconds.