The discussion did not proceed smoothly. Deidre said the fall was an accident; I put it to her that her child was a sociopath. Ms Simon nodded gravely. Eventually, after we’d been circling each other for fifteen minutes, Ms Simon said, ‘I think we should bring the children in.’

They entered with their usual attitudes: Samuel’s wide-eyed trepidation, Luna’s thuggish nonchalance.

Ms Simon put a twinkle in her eye when she addressed the children. I wanted to tell Samuel that it was a trap, that all charm is a trap, but it was too late – he was already mesmerised, sitting on one of the child-sized chairs that Gaby had added to the semicircle on our side of the desk, sticking as many knuckles in his mouth as he could fit.

‘Now,’ Ms Simon said, ‘no-one here is in any trouble. All right? We just want you to tell us everything that happened. Samuel, why don’t you go first?’

Something a cop would say. I wanted to tell Samuel not to say anything incriminating, or stupid. Connor put his hand on my thigh. I realised I had almost launched out of my seat.

Samuel kept his gaze on Ms Simon, locked on her, and I could see how she enjoyed this, could see the bullet point on her executive-level résumé: Key Skill: excellence in establishing rapport.

‘Luna pushed me,’ Samuel said. He said it all in a rush, like it escaped from him, like it pained him to admit it.

Ms Simon smiled.

Luna tried to interrupt. ‘No I didn’t!’ she began. ‘I didn’t! I —’

Ms Simon’s smile was calm and immovable. ‘Luna, you’ll have your turn in just a moment.’ She turned back to Samuel. ‘When did she push you?’

‘I was waiting my turn for slide.’

‘Were the two of you talking? Do you know why she pushed you?’

Tears appeared in his eyes. He shook his head. ‘Don’t know,’ he said. ‘Don’t know.’

Then he started crying in earnest. It was embarrassing how openly he wailed. Connor was the one who went to him, helped him blow his nose – which he did with great zeal and limited accuracy – and made the requisite murmuring noises.

‘Luna?’ said Ms Simon. ‘What do you remember?’

I almost smirked. It was impossible to prove a negative. Good luck, kid, I thought. It was only then, realising she wasn’t answering the question, that I really focused on Luna’s broad face. Her brows were tilted in confusion. Her cheeks were bright red. Her eyes were wet, though she didn’t cry. She looked at her mother, and her terror was real.

I saw that she was telling the truth.

‘I didn’t,’ she said, finally, her chest heaving with rapid breaths.

Wow, I thought. She really is a child. She seemed fragile, unformed; I suddenly sensed the weight of my advantage over her.