She heard Joachim’s boots on the stairs.

A moment later he was in the kitchen. He had the canvas bag in his hand. His face was angry. He looked at Carla and Ada. ‘One of you has been looking inside this bag!’ he said.

Carla spoke as calmly as she could. ‘I don’t know why you should think that, Joachim,’ she said.

Maud appeared behind Joachim and came past him into the kitchen. ‘Let’s have coffee, please, Ada,’ she said brightly. ‘Joachim, do sit down, please.’

He ignored her and scrutinized the kitchen. His eye lit upon the top of the low cupboard by the window. Carla saw, to her horror, that although she had put the camera away, she had left the two spare film cassettes out.

‘Those are eight-millimetre film cassettes, aren’t they?’ Joachim said. ‘Have you got a miniature camera?’

Suddenly he did not seem such a little boy.

‘Is that what those things are?’ said Maud. ‘I’ve been wondering. They were left behind by another pupil, a Gestapo officer, in fact.’

It was a clever improvisation, but Joachim was not buying it. ‘And did he also leave behind his camera, I wonder?’ he said. He pulled open the drawer.

The neat little stainless-steel camera lay there on a white towel, guilty as a bloodstain.

Joachim looked shocked. Perhaps he had not really believed he was the victim of treachery, but had been blustering to compensate for his sexual failure; and now he was facing the truth for the first time. Whatever the reason, he was momentarily stunned. Still holding the knob of the drawer, he stared at the camera as if hypnotized. In that short moment Carla saw that a young man’s dream of love had been defiled, and his rage was going to be terrible.

At last he raised his eyes. He looked at the three women around him, and his gaze rested on Maud. ‘You have done this,’ he said. ‘You tricked me. But you will be punished.’ He picked up the camera and films and put them in his pocket. ‘You are under arrest, Frau von Ulrich.’ He took a step forward and grabbed her arm. ‘I am taking you to Gestapo headquarters.’

Maud jerked her arm free of his grasp and took a step back.

Joachim drew back his arm and punched her with all his might. He was tall, strong and young. The blow landed on her face and knocked her down.

Joachim stood over her. ‘You made a fool of me!’ he screeched. ‘You lied, and I believed you!’ He was hysterical now. ‘We will both be tortured by the Gestapo, and we both deserve it!’ He began to kick her where she lay. She tried to roll away, but came up against the cooker. His right boot thudded into her ribs, her thigh, her belly.

Ada rushed at him and scratched his face with her nails. He batted her away with a swipe. Then he kicked Maud in the head.