In summer the lakeside would be crowded with families and children playing on the beach and paddling in the shallows, but today there were just a few walkers, well wrapped up against the chill, and one hardy swimmer with an anxious wife waiting at the waterside.

The home, which specialized in caring for severely handicapped children, was a once-grand house whose elegant reception rooms had been subdivided and painted pale green and furnished with hospital beds and cots.

Kurt was now eight years old. He could walk and feed himself about as well as a two-year-old, but he could not talk and still wore diapers. He had shown no sign of improvement for years. However, there was no doubt of his joy at seeing Ada. He beamed with happiness, burbled excitedly, and held out his arms to be picked up and hugged and kissed.

He recognized Carla, too. Whenever she saw him she remembered the frightening drama of his birth, when she had delivered him while her brother Erik ran to fetch Dr Rothmann.

They played with him for an hour or so. He liked toy trains and cars, and books with highly coloured pictures. Then the time for his afternoon nap drew near, and Ada sang to him until he went to sleep.

On their way out a nurse spoke to Ada. ‘Frau Hempel, please come with me to the office of Herr Professor Doctor Willrich. He would like to speak to you.’

Willrich was Director of the home. Carla had never met him and she was not sure Ada had either.

Ada said nervously: ‘Is there some problem?’

The nurse said: ‘I’m sure the Director just wants to talk to you about Kurt’s progress.’

Ada said: ‘Fräulein von Ulrich will come with me.’

The nurse did not like that idea. ‘Professor Willrich asked only for you.’

But Ada could be stubborn when necessary. ‘Fräulein von Ulrich will come with me,’ she repeated firmly.

The nurse shrugged and said curtly: ‘Follow me.’

They were shown into a pleasant office. This room had not been subdivided. A coal fire burned in the grate, and a bay window gave a view of the Wannsee lake. Someone was sailing, Carla saw, slicing through the wavelets before a stiff breeze. Willrich sat behind a leather-topped desk. He had a jar of tobacco and a rack of different-shaped pipes. He was about fifty, tall and heavily built. All his features seemed large: big nose, square jaw, huge ears, and a domed bald head. He looked at Ada and said: ‘Frau Hempel, I presume?’ Ada nodded. Willrich turned to Carla. ‘And you are Fräulein . . . ?’

‘Carla von Ulrich, Professor. I’m Kurt’s godmother.’

He raised his eyebrows. ‘A little young to be a godmother, surely?’

Ada said indignantly: ‘She delivered Kurt! She was only eleven, but she was better than the doctor, because he wasn’t there!’

Willrich ignored that. Still looking at Carla, he said disdainfully: ‘And hoping to become a nurse, I see.’