‘Consider the conditions in which we live here,’ Pfaus resumed enthusiastically. ‘You see no fire in this apartment, Joseph, yet it is beautifully warm, is it not, on this cold January night?’

Swallow had been aware of the pleasant, even temperature of the apartment from the moment he had arrived.

‘Yes, indeed.’

‘Central heating,’ Pfaus said. ‘Many of the new buildings in the city have it. Coal from the Ruhr is burned in the basement furnace, driving heated water through the whole system.’

When they had finished their Wiener Schnitzel, Elena served a fruit tart with a warm raspberry syrup. Then she excused herself from the table.

‘I’m going to retire to allow you gentlemen to converse. Good night, Mr Swallow. It’s been a great pleasure to meet you.’

Swallow noted that as the evening had progressed, Elena Pfaus’s American pronunciation had become more accentuated. He had the sense that she was more than a little happy to connect to things that brought her back to the life she had left behind in the United States.

He stood and shook her hand politely.

‘Thank you, Mrs Pfaus, for a fine dinner and lovely company. Good night.’

Pfaus poured a peach brandy for each of them when Elena had gone. Then he opened a small wooden box, decorated with images of fierce-looking military men in helmets with impressive moustaches. Swallow declined the offered cigar.

‘So,’ Pfaus said, striking a match and drawing deeply on his own cigar, ‘tell me what progress you made with our young Mr Carmody.’

Swallow sipped at the peach brandy. It was sticky and too sweet for his taste.

‘He says he had nothing to do with the murder. And I’m inclined to believe him. He’d have liked to develop some romantic interest with the girl, but she rejected him, he says. I think he could be a helpful witness about the circumstances leading to the death, and he wants to do a deal with me.’

‘What sort of deal?’

‘I didn’t want to start negotiations with him tonight. Better to let him sweat for a bit. But I imagine he’ll want to be freed from any charges here and allowed to go free in return for his assistance.’

Pfaus shrugged.

‘That’s not a problem as far as the Kriminalpolizei are concerned, Joseph. We don’t want him here. He’s costing the German Empire money, so you’re welcome to have him if you think he can be of help to you.’

Swallow sipped again at the peach brandy. It was definitely too sweet for his taste, but he felt he might give offence if he left it unfinished.

‘I think he can, Johann. You mentioned something earlier that might actually have a bearing on this case. Tell me more about the law here in Germany about compensation for people who are injured at work.’