Her English had a distinctive American pronunciation.

‘I understand from Johann that you are here on police business, so I hope that this evening may be a pleasant distraction for you. Come, sit and have a glass of wine and tell me what it is that brings you to Berlin.’

There was a hint of reprimand in Johann Pfaus’s tone.

‘Oh, Mr Swallow is investigating a brutal murder case. You have no need to be upset by any details.’

Elena smiled knowingly, but did not answer. Swallow sensed that there were two strong spirits in the Pfaus household.

Three places were set for dinner at a circular table by the window, with good china and heavy crystal glassware, set on a lace-trimmed tablecloth. Pfaus poured them a dry Riesling.

‘You have a very nice home, Mrs Pfaus,’ Swallow said.

Elena smiled contentedly.

‘Thank you, Mr Swallow. We don’t have many guests because Johann works so hard. For me it is a very special evening when we have a visitor from England.’

Swallow was not going to bother explaining that he was not from England. But Pfaus anticipated the point.

‘Inspector Swallow is not from England but from Ireland, my dear. From Dublin. He has reminded me more than once since we met that the Irish and the English are not the same race. You remember there were many Irish people in New York?’

Swallow thought he detected something close to momentary disappointment in Elena Pfaus’s expression.

Before she could respond, two small voices came in unison from behind him.

‘Good night, Papa. Good night, Mama.’

He turned to see two little girls, dark-haired like their mother, in their night attire standing in the doorway. Swallow guessed the slightly taller child might be seven, with her sister perhaps two years younger.

‘Ah,’ Pfaus beamed. ‘Meet our two precious jewels, Anna and Louise. They are just on their way to bed.’

He stood from the table and took them, one in each hand, to meet the visitor. They shook hands gravely and said something in German that Swallow could not understand, so he nodded and smiled.

‘It’s a pleasure to meet you,’ he said as warmly as he could. He realised how little he knew about dealing with young children. He had hardly ever spoken to one since his own childhood, other than on special occasions when he brought sweets or perhaps chocolate to Pat Mossop’s brood. He nodded and smiled again and tried to summon the few words of German that he knew.

‘Danke schön . . . danke schön.’

The children first giggled, then nodded solemnly and smiled as they backed towards the door to go to their beds.

‘Do you have children, Mr Swallow?’ Elena Pfaus asked.

‘Regrettably, no, Mrs Pfaus. I married rather late in life. Just very recently in fact. But I am happy to say that my wife, Maria, is due to be delivered of our first child later this year.’