A man on the stairs pointed towards the empty darkness where the train had been standing a few moments ago. ‘He went that way – on to the tracks!’

  Brandt and Schwab raced to the edge of the platform. Schwab heard something, a scuffing sound followed by a quick, involuntary exclamation of pain. She aimed her torch towards it and caught a flicker of movement. ‘Over there!’ she shouted. But whoever it was out there had evaded her beam.

  Brandt jumped down on to the tracks. ‘Come on!’ he shouted. ‘He must have gone this way!’

  Brandt started jogging back up the tracks towards Rummelsburg Depot, in the direction the train had just come from.

  Moving more tentatively, Schwab lowered herself on to the track. Brandt was up ahead of her, his torch pointing just a few metres in front of him to light his way across the railway sleepers. To their left a second set of tracks ran parallel to the ones they were on. Just then Schwab heard or perhaps just sensed something: a humming vibration coming down the tracks, followed by a distant clattering sound coming from behind her. It took her a moment to work out what it was.

  ‘Train!’ she yelled. ‘Brandt! Watch out! It’s a train!’

  Brandt stopped dead. The clattering was louder now – much louder. Schwab swung round and pointed her torch back down the tracks. An S-Bahn train was heading straight towards them, a huge dark shadow bearing down at tremendous speed.

  Schwab had proved her courage well enough already that night, but she couldn’t prevent the scream of utter terror as she stood helpless in the path of the train.

  It sped by on the track to her left, so close that the rush of air almost knocked her off her feet. When it had gone she heard a nervous laugh from up ahead. ‘Phew! That was close!’ Brandt exclaimed, the forced laughter in his voice barely disguising the fact that he’d been just as frightened.

  ‘It’s no good,’ she said. ‘We’ll never find him out here. He probably knows these tracks like the back of his hand and we have no idea where we’re going.’

  Brandt sighed. ‘You’re probably right. And the next train from Rummelsburg Depot will be coming along the line we’re on any minute from now. Damn it! We were so close to him!’

  ‘Count yourself lucky, Brandt,’ Schwab muttered under her breath. ‘You weren’t half as close as me.’ Then she spoke up more clearly. ‘Come on then. Back to the station before we both get flattened.’

  *

  It was my job to interview Helga Schwab when she returned to the station. Papa Schmidt had been doing the same with Brandt. We compared both accounts and wrote up an incident report that we checked with the officers concerned and then handed over to Lüdtke.

  Schwab and Brandt were both angry and bitterly frustrated at their failure to catch the killer. ‘You are not to blame,’ Lüdtke assured them. ‘I have had months to catch him and have not come anywhere near doing so. You at least came close.’

  Yet a pall of depression seemed to settle over the murder squad in the days and weeks that followed. We had been offered a chance, however fleeting, and failed to take it. Now the only thing that we could do was hope that we would get another before another woman paid for our failure, just as the seven before her had done.

  19

  Winter slowly warmed into spring. The snow melted, the first buds appeared on the trees, the seasons changed. But the S-Bahn murderer was still out there somewhere, and still as elusive and as mysterious as ever. There was another late-night encounter in a deserted carriage: this time at Erkner, the terminus of the No. 3 line. A guard was doing a final check on an empty train that was about to be shunted into the sidings for the night when he disturbed a man, dressed in dark clothes. He called the alarm and chased the man across the tracks. Shots were fired. But once again the man, and surely we can say that it was the killer himself, disappeared into the pitch-black night.

  More weeks went by and there was no further sign of him. One month after another passed without an attack. Now we began to ask ourselves whether we had finally chased him away from the S-Bahn, and, if so, were we merely shifting the problem somewhere else. Or had he disappeared from the city altogether? It was perfectly possible that he’d been called up for service in the armed forces, but we dared not assume that the killing spree was over. We had to keep patrolling the trains, guarding the stations and going through the information we had in our possession again and again, reading the files until they became as deeply engraved in our memories as ancient inscriptions on a stone monument.

  Lüdtke was convinced that the murderer had to be, or have been, an S-Bahn worker in the Rummelsburg area. Geographically it sat at the heart of both of the killer’s areas of operations: the gardens and allotments of Friedrichsfelde and the trains of the No. 3 lines. Administratively it had been at the heart of all our police operations on the S-Bahn: a place where the killer would be able to monitor what we were up to and adapt his plans accordingly. And it was also one of the busiest sections of the entire Berlin rail network: a great complex of lines, junctions, sidings and signal boxes, where crowds of workers came and went all the time and one man could easily lose himself in the crowd of people or the web of intersecting tracks.

  In circumstances such as these, when all seems hopeless, there is nothing for a junior officer to do but trust in his superiors, obey their orders and work to the maximum of his ability. That was therefore what I did. By sheer hard work, Lüdtke and I cross-referenced the working hours and known movements of hundreds of S-Bahn employees and came up with a list of eight who might all have been able to commit the seven murders and six serious but non-fatal assaults that we had connected with the S-Bahn murderer.

  It was hugely tempting to bring them all in and try to interrogate or if necessary beat a confession out of them. The problem was that every one of the eight had already been interviewed at length without saying anything that had given rise to any suspicion. Nor had anyone else given any evidence that might incriminate any of the eight. There was thus no good reason for us to detain them, and even if we had done so, we had no material to work with during an interrogation. A police officer, like a prosecutor, is always in a much stronger position if he already knows the answer to the question he is asking. It is one thing to make a man admit to a truth that you have already discovered for yourself. It is quite another to take potshots in the dark, hoping that you are lucky enough to strike a target.

  We were, therefore, completely impotent until something else happened that gave us something more to work on. And then something did happen, and it made not a blind bit of difference. Another woman was hit on the head and sexually assaulted in Friedrichsfelde. Luckily for her she survived. Unluckily for us, the blow dazed her so badly that she was unable to remember anything of the incident, or her assailant. Once again we had nothing to tell our increasingly impatient masters at the Reich Security Main Office, and we could only be grateful that they had so much else on their minds that they didn’t have the time to take a more active interest in our case.

  Something was up. All through April, May and June, Criminal Police officers were disappearing from Alex and transferring to a mysterious training centre at an old border police college in east Prussia. There they worked under circumstances of total secrecy. Whatever was happening there, it went all the way to the very top, because Arthur Nebe himself was involved. He’d been offered some sort of new command. Apparently he’d done everything he could to avoid it, but Heydrich was insistent. He needed his very best officers for this task, whatever it was, and even a man of Nebe’s exalted status could not say no.

  On 22 June 1941 we discovered what all the fuss was about. For that was the day that Operation Barbarossa began: the invasion of Russia, the single biggest undertaking in the entire history of warfare. The Wehrmacht launched the greatest of all its blitzkriegs and smashed through Stalin’s Red Army with even more devastating success than it had through the British and French a year earlier. In the wake of our armies came a second wave of invaders, four SS task forces known as Einsatzgruppen, and lettered A to D. Their officers were almost all drawn from the Criminal Police, Gestapo and SD, while their lower ranks tended to comprise uniformed police officers, many of them middle-aged and therefore too old to fight in the army itself, organized into so-called Police Battalions.

  We assumed that their job was to carry out the police work that was bound to be needed as we occupied the vast new territories that were falling into our hands, seemingly by the hour. Biene and I, like men and women all across Germany, sat enthralled as the newsreels showed our Panzer divisions smashing through Russian defences, while the infantry rounded up hordes of defeated Soviet prisoners of war. The numbers were so vast as to be almost meaningless: thousands of enemy tanks destroyed; tens of thousands of their men killed; hundreds of thousands captured.

  We were shown the desperate panic measures of the fleeing Bolsheviks as they set fire to their own crops and cities; the ugly and pathetic forms of the subhuman Slavs we had defeated; and the hooked noses and deceitful expressions of the Jews who populated the vast spaces of Russia that would now be opened up for colonization by healthy, civilized Germans. Yet although we rejoiced at the victories won by our brave soldiers and airmen, Biene and I weren’t too concerned by the politics that lay behind the Russian campaign. We were too busy falling in love.

  She remained insistent that none of this should ever be apparent from our day-to-day conduct in the office. Lüdtke knew of our blossoming relationship, but we somehow managed to keep it secret from everyone else. In this we had been greatly helped by the sudden ending to our first date. The police driver had taken me back to Alex and Biene to her boarding house. At no time had we behaved as anything other than colleagues on a friendly but perfectly proper evening out. There had thus been very little for even the most imaginative gossips to work on, particularly when Biene was, if anything, rather cooler to me in public than before.

  By the beginning of July the Berlin murder squad appeared becalmed. One by one officers were drifting away to other, more immediate, cases as the S-Bahn murders seemed fated to be forever unresolved. After months of overwork, we even had time to waste on idle conversation. Baum had somehow convinced himself that he was going to get a transfer to Paris and could spend hours describing the apartment he would get himself and the beautiful Parisian women with silk stockings and scented skin who would join him there to make love, drink champagne and nibble on foie gras.

  Then the killer struck again.

  In the early hours of 3 July the body of a 35-year-old woman called Frieda Koziol was discovered on a path through an area of allotments in Friedrichsfelde. She’d been smashed over the head and raped. Suddenly the high-ups at the Reich Security Main Office were paying attention again. They wanted action now.

  By the end of the day, all eight of Lüdtke’s suspects were in detention. If one of them wasn’t the S-Bahn murderer we had nowhere else to go.

  20

  Ludwigsburg and Moscow: October 1961

  A senior Foreign Office official came to see Kraus and Siebert to dissuade them from travelling to Moscow. He was tall, thin, silver-haired and dressed in a grey suit whose perfect fit and impeccably understated cut was surely the work of a London tailor. His name was Klaus Graf von Schenk und Lichtenburg, and he looked at them with the same lordly disdain with which his ancestors must have regarded the peasants on their aristocratic estates.

  ‘We are, as you know, in a state of crisis, possibly on the brink of another war, and there are many people who believe that your visit to Moscow will play into Russian hands,’ he said. ‘The Soviets would not have contemplated opening up their files to you unless they saw an advantage in it for them. Clearly they think that the information they are giving you will serve to discredit our nation. If you have any love whatever for your Fatherland, you should think twice and ask yourself: is this trip really necessary? Must we place ourselves in debt to the Soviet Union? And do we really want to assist our enemies?’

  Kraus was an old socialist at heart. He had no time for titles and fancy names. ‘Forgive me, Herr Lichtenburg, if I ignore your warning. I have spent the past three years being told why I shouldn’t do the work I do and not one of the many arguments made against me has persuaded me to stop. If the Russians are stupid enough to think that I’m in any way helping their cause, good luck to them. All I care about is that the papers they’re giving us might just make it easier to achieve a successful prosecution and lock guilty men behind bars. In the meantime, I’m leading an official, federal investigation into indicted criminals and I need no further justification than that.’

  ‘Very well, then, I can see there is no purpose in trying to dissuade you,’ Lichtenburg conceded. ‘But if you must go to Moscow, there are things you need to know.’

  ‘Go ahead. I’m all ears.’

  Now Lichtenburg dropped the diplomatic rhetoric and spoke with the blunt, pragmatic assurance of a man who knows his subject. ‘Bear in mind, above all, that you will be under observation at all times: night and day, awake and asleep. You will have a minder who will probably be introduced to you as an official from the Ministry of Justice. Assume that he is a KGB agent. Assume, too, that he is not the only person watching you wherever you go. Your hotel rooms will be bugged. The table in the hotel restaurant will be bugged. The offices where you work will be bugged.’

  ‘Sounds like old times,’ Kraus observed.

  ‘Actually, that’s not a bad comparison. Just imagine the Gestapo are watching you. Trust no one. Suspect everyone. And assume that anyone who approaches you is doing so under orders. Never accept a drink from anyone, especially an attractive member of the opposite sex. It is distressingly common for foreigners to be drugged, knocked unconscious, photographed in a compromising position and then blackmailed. Likewise, you may well be approached by someone, usually an elderly man, claiming to have been given permission to emigrate so that he can join his family in Australia, or wherever. He will explain that he requires foreign currency for his journey and offer to exchange roubles for your marks at a very generous rate. Foreign currency dealing is absolutely illegal in Russia. If you hand over so much as a single mark, you will be arrested and threatened with a lengthy jail sentence unless you cooperate with the Soviet authorities.’

  ‘I don’t think I’m likely to be giving old Russians my money!’ Kraus joked.

  ‘This is no laughing matter, Dr Kraus. This happens. There is nothing remotely amusing about being in a KGB cell in Lubyanka Square, facing ten years in a Siberian labour camp.’

  ‘What should we expect from the city itself?’ Paula asked, feeling the tension between the two men returning and wanting to move things on.

  ‘I’ll tell you something about Moscow that you won’t find in any guidebook,’ Lichtenburg replied. ‘As you drive in from the airport, you’ll pass mile upon mile of apartment blocks. None of them is more than ten years old, but many are already falling apart. That’s because they were built by Russians. The best new blocks in Moscow – the ones reserved for senior Party officials and foreign diplomats – do not fall apart. You know why? Because they were built by Germans. Captured soldiers, taken during the war on the Eastern Front who …’ Lichtenburg stopped in mid-sentence. Paula was looking at him with an expression of utter desolation.

  ‘I’m so sorry, Dr Siebert,’ he said, with genuine remorse. ‘I didn’t mean to upset you. Here …’ He took the silk hand-kerchief from his breast pocket and offered it to her.

  ‘No thank you … you’re very kind but I’ll be all right. It’s just, well, my father was killed very close to Moscow – during the war, I mean …’

  ‘Then you should be glad for him that his end was swift,’ said Lichtenburg. ‘The men who were captured were condemned to a hellish existence. Many died within weeks or a few months of captivity. Others lasted years. The lucky ones finally came home, broken men most of them. But there are more still in Russia, thousands, maybe tens of thousands of them, and try as we might, we cannot get them back. The Russians hate us. They will never forgive us and they would stick you both in one of their camps without a second thought. So I feel obliged to repeat my first advice: do not go to Moscow. And if you insist on going, spend every second of your time there in fear. That, I would suggest, is the best way of ensuring that you come back home again, safe and sound.’

  *

  Sheremetyevo International Airport was less than two years old, yet it had already acquired the tatty, drab, grey patina that Paula would soon come to associate with the Soviet capital. Their baggage was brought to them by a porter and inspected with a thoroughness bordering on paranoia by the customs men. As each item of her clothing, underwear included, was fingered and examined, Paula felt an almost physical sense of violation. They had been on Russian soil for less than an hour but already she understood that, far from being absurd exaggerations, Lichtenburg’s warnings were no more than the simple truth. Two people met them: a Soviet official from the Ministry of Justice, who introduced himself as Poliakov, and Neumann, a representative from the West German embassy. ‘I’ll just come with you to the hotel,’ Neumann said with forced breeziness. ‘Make sure you’re both settled in properly.’

  It was a cold, dark, damp autumn day and they drove in on a road that was as wide as an autobahn, yet almost empty of traffic. A few kilometres from the airport they passed some kind of installation, like a modern art sculpture: great clusters of concrete beams, gathered on either side of the road, like the skeletons of giant, brutalist wigwams.

  ‘What on earth is that?’ Paula asked.

  Poliakov twisted round from the front passenger seat. There was a smug smile on his face and he made no attempt to hide the triumphal pleasure in his voice as he said. ‘That is the Khimki War Memorial. Those are tank traps and they mark the furthest point reached by the fascist forces in the Great Patriotic War. This is where we held them and smashed them. We never took another backward step from here, all the way to Berlin.’