The chamber was at least eight feet deep and six feet long by four feet wide, with a couple of steps leading down into the darkness. Like a front-line bunker, it had supporting beams, walls fortified with planking and duckboards at the base. It was reasonably dry but the smell was musty and it was cold and unfriendly. No place for a child.

Wilde wondered how long the hide had been there. At what age did Matthias Rieger first bring her here and instruct her in its use? He must have trained her well over the years to seek out this sanctuary without question when danger threatened. But how long would she have stayed here if they had not come and found her?

Right now she was terrified. Like a cornered animal.

The girl did not say a word, but her eyes were wide. Wilde was sure he could hear her teeth chattering. Poor child, she must have been cowering in the darkness for an hour, perhaps two. She must be freezing. Of course, he could step down into the cave and lift her out, but much better if she were to emerge of her own volition; it would not be a good start to use physical coercion of any kind on the girl. If this was to work, if they were to preserve the ‘package’, she would have to learn to trust them in very short order.

Sunny had a box of matches and lit one beneath her own face, so that the girl could see her, and smiled kindly. She lit two more.

‘Won’t you come out, dear Klara? We are here to help you. And I know I must say to you that Bismarck loves carrots.’

Wilde heard a gasp of recognition from the girl.

‘Come on, liebling, come out. My name is Sunny, and this is my friend Tom. Your father, Matthias, sent us. Bad men came to your house, but now you will be safe with us. I promise you this with all my heart.’

Slowly, the girl’s head rose from the gloom. She had long wavy fair hair, though now it was caked in mud and dust. And then came her face, wide-eyed and full, much like the picture of her true mother Geli Raubal – the one Wilde had been shown by Jim Vanderberg in the American embassy.

She climbed the steps that her father had built, looked nervously in all directions, then stepped out into the light of day. She was wearing a coat over her nightgown, and school shoes without socks and she was shivering.

Sunny smiled and held out her hand.

Klara looked at the woman’s hand, then gave a stiff little bow of her head, but instead of taking the hand, she threw out her right arm in a salute.

‘Heil Hitler,’ she said.

Sunny seemed taken aback, but quickly responded in kind.

‘Heil Hitler.’