‘Birds?’ Knackfuss kicked the broken glasses across the floor. He walked close to Joe, loomed over him. ‘You have to do better,’ he said. ‘Why would a woman be interested in birds?’

Joe thought of Geoffrey’s words, Jerry wouldn’t take it kindly if they thought you were spying on them.

‘I wasn’t spying,’ Joe said. ‘If that’s what you think.’

Or Trude. Did they think Trude was a spy? A traitor? She had that note in her basket making fun of Hitler. She’d been protecting Joe when she left him that last time. She knew she was being watched.

‘Where is Trude?’ Joe said. ‘What have you done with her?’

‘Trude,’ he said. ‘Trude. We have a name.’

‘What have you done with her?’ Joe was too small to throw his voice and he could hear it break as he shouted. ‘Where is she?’

He knew how ruthless the Germans were now. Had seen it for himself.

Knackfuss walked to his desk, picked up the telephone. He spoke in German, put the receiver down as the door opened and two Feldpolizisten entered. Knackfuss nodded. One of them came up to Joe, two large strides, clamped handcuffs round Joe’s wrist, tugged him away.

‘We will go somewhere more comfortable,’ Knackfuss said. He picked up a folder from his desk. ‘Lead on,’ he said to the Feldpolizisten. ‘I will follow.’

Joe’s trousers chafed as he walked. He had to skip to keep up with the Feldpolizisten, along a corridor, through a door, down two flights of stairs, into the basement. Thick pipes ran along the ceiling and the walls had not been painted for years. Joe smelled the acrid stench of a furnace, glimpsed it as they passed a room, a big, ugly beast devouring the coal that surrounded it, even in the summer heat.

They stopped at a door, Verhörraum. Went inside. The only light hung from a dim bulb in the centre. There was a table and four chairs arranged around it, and to the left, another door. Joe was pushed towards one of the chairs.

‘Sit.’

The Feldpolizisten stood behind him. Knackfuss sat on a chair opposite him, laying the folder on the table and opening it.

The walls were dirty and stained, and the floor cracked and broken. Joe’s wrist was red from where the handcuffs pinched. He wanted to ask, Why I am being held like this? He’d done nothing wrong. He was an Irish citizen and didn’t that count for something? He opened his mouth, shut it.

He didn’t dare.

Joe wasn’t sure how much time had passed before the door opened and another man came in. Joe could tell from his uniform that he held high rank. He wore shoulder straps, with GFP embossed in metalled letters. Geheime Feldpolizei.

‘Oberleutnant Zepernick,’ Knackfuss said, standing up, holding out his hand. ‘Busy day, eh?’