Richter headed south on Warschauer Strasse, crossed the railway, then turned into a cheap industrial neighbourhood of warehouses, yards and small factories. There was a group of soldiers toting kitbags outside a back entrance to the station, no doubt embarking for the Eastern Front. And a fellow-countryman somewhere in this neighbourhood doing his best to betray them, Macke thought angrily.

Wagner pointed down a narrow street leading away from the station. ‘He’s in the first few hundred yards, but he could be on either side,’ he said. ‘If we take the van any closer he’ll see us.’

‘All right, men, you know the drill,’ Macke said. ‘Wagner and Richter take the left-hand side. Schneider and I will take the right.’ They all picked up long-handled sledgehammers. ‘Come with me, Franck.’

There were few people on the street – a man in a worker’s cap walking briskly towards the railway station, an older woman in shabby clothes probably on her way to clean offices – and they hurried quickly past, not wanting to attract the attention of the Gestapo.

Macke’s team entered each building, one man leapfrogging his partner. Most businesses were closed for the day so they had to rouse a janitor. If he took more than a minute to come to the door they knocked it down. Once inside they raced through the building checking every room.

The pianist was not in the first block.

The first building on the right-hand side of the next block had a fading sign that said: ‘Fashion Furs’. It was a two-storey factory that stretched along the side street. It looked disused, but the front door was steel and the windows were barred: a fur coat factory naturally had heavy security.

Macke led Werner down the side street, looking for a way in. The adjacent building was bomb-damaged and derelict. The rubble had been cleared from the street and there was a hand-painted sign saying: ‘Danger – No Entry’. The remains of a name board identified it as a furniture warehouse.

They stepped over a pile of stones and splintered timbers, going as fast as they could but forced to tread carefully. A surviving wall concealed the rear of the building. Macke went behind it and found a hole through to the factory next door.

He had a strong feeling the pianist was in here.

He stepped through the hole, and Werner followed.

They found themselves in an empty office. There was an old steel desk with no chair, and a filing cabinet opposite. The calendar pinned to the wall was for 1939, probably the last year during which Berliners could afford such frivolities as fur coats.

Macke heard a footstep on the floor above.

He drew his gun.

Werner was unarmed.

They opened the door and stepped into a corridor.

Macke noted several open doors, a staircase up, and a door under the staircase that might lead to a basement.

Macke crept along the corridor towards the foot of the stairs, then noticed that Werner was checking the door to the basement.