Her knock was tentative, and there was no answer. She knocked again, a little louder. Still nothing. Finally, she rapped hard. When there was no reply, she turned to Wilde and shrugged. He made a motion with his hand as though twisting a doorknob. She nodded, and the door opened.

Light flooded out. She turned back to Wilde.

‘Call out to them,’ he said, his voice little more than a whisper.

She stepped inside the house.

‘Frau Rieger . . . Herr Rieger.’ Her voice was friendly and unthreatening. ‘Hallo?’

And then she was staggering backwards out of the door, her hand to her mouth, moaning as if overcome by some unspoken horror.

*

Matthias Rieger had prayed that this day would never come. He and Maria were devout Christians and each night they had knelt together by their bed and communed with the Lord, entreating Him to protect their adopted daughter and keep her safe. She had, after all, been a gift from God, long after they had resigned themselves to childlessness.

Now, it seemed, their prayers had not been enough. The barking of the dog in the middle of the night had seen to that. God giveth, man taketh away.

But, of course, it hadn’t been God who delivered the baby to their welcoming arms. It had been dear Father Huber and the likeable but rather earnest midwife, Romy Dietrich.

They knew the truth about the baby’s birth and had passed it on to Matthias and Maria, swearing them to secrecy. Even before the man with the toothbrush moustache became Chancellor, they knew it was a secret that would have to be kept for ever, for he was surrounded by dangerous and desperate people. But secrets have a habit of eventually emerging into daylight. And then . . . And then . . .

Matthias Rieger had been considering retirement for several years now. He was sixty and his poor, ailing wife was sixty-two, and she required more of his time to care for her, especially with the needs of a ten-year-old to be considered. But it was not just these matters that made him want to leave the teaching profession. He was also increasingly uncomfortable with the National Socialist curriculum. Why did the boys and girls have to wear the uniforms of the Hitler Youth and the League of Girls in the classroom? Why did the school principal insist that every teacher should give lectures on race at least twice a week, even if their subject had no possible connection? The children they taught knew nothing of these people from other countries and so, in their trusting way, they soaked all this poison up and rejoiced in the knowledge that they, as good Nordic Aryan Germans, were superior to all.

One day Klara came home with a song that she and her classmates had been taught. She sang it to Matthias and Maria at the dinner table: Adolf Hitler is our saviour . . . for Hitler we live, for Hitler we die . . . Hitler is our Lord, who rules a bold new world . . .