David Downing - Potsdam Station

'Yes,' Rosa added, offering him a small hand to shake. Taking it, he found himself fighting back tears.

It was around two in the morning when Paul reached the Zoo Bunker flak towers. He had hitched a lift across town in a Ministry of Propaganda lorry – the Reich's few remaining tanks might be crying out for fuel, but delivering the latest edition of Panzerbar obviously had a higher priority. Skimming a copy by the light of the burning buildings on Tiergarten Strasse, he had discovered that treachery was rife and help on its way.

Despite the sporadic shellfire, tanks and infantry were scattered among the trees outside the Gun Tower, offering an illusion of control which shattered the moment he stepped inside the vast concrete edifice. Here the only deterrent to utter chaos was the degree of overcrowding, which rendered physical movement almost impossible. Every stairway, landing and room of the multi-storey block was occupied by a bewildering mixture of civilians and soldiers, all jostling for enough space in which to lie down.

It took Paul more than half an hour to seek out any semblance of military authority, and when he did the news was bad. The Untersturmfuhrers at the Potsdam Station shelter had got their facts wrong – the remains of the 20th Panzergrenadier Division had been sent to Wannsee Island in the south-western outskirts, and the Russian occupiers of Dahlem and Grunewald now stood between Paul and his former comrades. A weary major suggested he attach himself to the 18th Panzergrenadiers, who were actually on the premises, but Paul's request for a precise location went unanswered. There were, the major added in explanation, over twenty thousand people crammed into the tower.

Paul went off in search of somewhere to sleep, and eventually found a large enough space to sit down in, provided his chin touched his knees.

As Saturday morning wore on it became increasingly clear to the inhabitants of the Potsdam Station shelter that some sort of crisis was brewing. More and more soldiers were arriving, many of them foreigners serving in the Waffen-SS. They had the air of men expecting to die, and no interest at all in those hoping for reprieve. If death was catching, they seemed like carriers.

'The doctors are all moving to the Zoo Bunker,' Annaliese told Effi.

'And the nurses?'

'Unofficially, we've been told to choose our own fate. We can go along, or stay here, or whatever we want. There's a group of us going west through the tunnels – one of the soldiers used to work for the S-Bahn and he says he can get us most of the way to Spandau.'

'What's so great about Spandau?'

'Nothing much. Gerd's parents live out there, so if all else fails I'll have somewhere to stay. But people say you can still get out of the city from there, and I'd like to leave the Russians behind. The Americans may not be any better, but they can hardly be worse. You should come with me. Both of you.'

'I have a sister to find' Effi said automatically. It occurred to her that the U-Bahn tunnel towards Spandau passed under Bismarck Strasse. 'But can we come with you as far as Knie?' she asked.

'Of course. The more the merrier. We're leaving now, by the way – I only came up to see if you wanted to come. And to say goodbye if you didn't.'

Effi picked up their suitcase. 'Let's go.'

Their route to the platforms took them through the hospital, which was still crowded with wounded.

'What will happen to them?' Effi heard herself ask. She already knew the answer.

'There's no way of moving them,' Annaliese confirmed. 'The Russians will have to look after them.'

They emerged into a wide corridor still plastered with Promi slogans, and descended a staircase lined with identical posters bearing the single word 'Persevere!' As they emerged onto the dimly lit platform, Annaliese spotted their group of around a dozen people. There was only one other woman, dressed somewhat incongruously in a long fur coat and hat. Most were middle-aged men in civilian clothes, without weapons or insignia. Minor government officials most likely, the holes still showing in their suit lapels where they'd pinned their badges of loyalty. A couple of Hitlerjugend bearing rifles made up the party; they were busy telling all who would listen that they were just heading back to their Ruhleben barracks.

After checking that everyone was present – the whole business had the air of a school outing, Effi thought – the ex-railway worker led them off the platform and down another staircase. They were still descending when a dull boom reverberated in the distance, then faded into silence. They all stood there listening for several moments, but there were no aftershocks, no sounds of roofs collapsing or soldiers approaching.

The lower of the two S-Bahn platforms was even more crowded, mostly with hungry-looking women and children. The ex-U-Bahn employee had just leapt down to the track bed when a low swishing noise became audible down the south-leading tunnel. It rapidly swelled in volume, rising above the cries of alarm, and exploded from the tunnel mouth in a surging wave of water. The ex-railway worker was knocked off his feet and carried along for at least twenty metres, before managing to fight his way out of the torrent.

All along the platform people were leaping to their feet, frantically gathering children and possessions, and looking round for the nearest exit. Most of the adults seemed to be shouting, most of the children crying. At the mouths of corridors scrums were already underway, as people fought for precedence in their desperation to get away.

Effi resisted the pull, fixing her eyes on the flooded track bed. The tide was slowing, the water rising, but the platform was a metre high and there seemed no immediate danger. Another few moments and they might have been inside the tunnel, with God only knew what results, but for now the platform seemed a much safer bet than the struggle on the stairs.

Rosa was standing beside her, staring open-mouthed at the dark, swirling water. As the tumult around the stairs grew less, they could both hear the screams of those trapped in the tunnels.

It was hot in the Zoo tower, and Paul awoke streaming with sweat from a few hours of miserable sleep. His body was stiff as a board, and there was a sharp pain in his back where the SS officer's machine pistol had pressed against it. He forced himself painfully to his feet, and watched the bodies around him expand into the few square centimetres he had relinquished.

The smells of sweat, shit and blood – the latter emanating from the continuous activities of the operating theatre on the ground floor – permeated the entire structure, and the loudly whirring air extractors seemed incapable of shifting them. What they did do, was force everyone to shout above them, which only exacerbated the overriding sense of barely suppressed hysteria.

It was, Paul thought, as if they'd all been placed in a huge coffin. The lid was on, with only the burial to look forward to.

He had to get out.

His stomach rumbled, reminding him that he'd hardly eaten since the previous morning. There had to be food somewhere in the tower, or people would be even more agitated. He would seek it out, and maybe stumble across the 18th Panzergrenadiers in the process.

He eventually found the canteen he had frequented as a flakhelfer, and joined the long queue. There was only wassersuppe on offer, but it would improve the taste in his mouth. There was even a table to sit at, and after emptying the tin mug he laid his forehead on his folded arms and closed his eyes.

But sleep wouldn't come. On first joining the army he'd slept through anything quieter than a katyusha barrage, but that knack, like so much else, had eventually deserted him.

Two seats down a young soldier with a Rhenish accent was insisting that Wenck's Army could only be hours away. No one in his group disputed this, although some comrades were more inclined to put their faith in the imminent appearance of the long-anticipated wonder weapons. One corporal had heard rumours of bombs that could destroy whole cities, and of their intended use against London this coming weekend. When another man argued that Moscow should be the target, the corporal could only agree with him. But, sad to say, the Soviet capital was temporarily out of range.