I asked, ‘Do you ever try and trace who put up a card? Like, if there was one that said “I’m on drugs”, you’d want to work out who wrote it. How would you go about that? Is there a CCTV camera on the board, anything like that?’

‘CCTV?’ Drawn out like a foreign word. Amusement, real or put on. ‘This is a school, Detective. Not a prison. And the students here don’t tend to be heroin addicts.’

I said, ‘How many students have you got?’

‘Almost two hundred and fifty. First year through sixth, two classes in each year, roughly twenty girls in each class.’

‘The board’s been up around five months. Statistically, in that amount of time, a few of your two hundred and fifty have had something in their lives that you’d want to know about. Abuse, eating disorders, depression.’ The words came out of my mouth strange. I knew I was right, but in that room they made a flat splat like I’d spit on the carpet. ‘And like you just said, girls want to tell their secrets. You’re telling me you never find anything more serious than “French class sucks”?’

Miss McKenna looked down at her hands, hiding behind her eyelids. Thought.

‘When identifying a writer is necessary,’ she said, ‘we have found that it can be done. We had one card that showed a pencil drawing of a girl’s stomach. The drawing had been sliced in a number of places by a sharp blade. The caption said, “I wish I could cut the whole thing off of me.” Obviously, we needed to identify the student. Our art teacher offered suggestions based on the style of the drawing, other teachers offered suggestions based on the handwriting of the caption, and within the day we had a name.’

‘And was she cutting?’ Conway asked.

Eyes hooded over again. Meaning yes. ‘The situation has been resolved.’

No drawing on our card, no handwriting. The cutter had wanted to be found. Our girl didn’t, or didn’t want to make it easy.

Miss McKenna said – to both of us, now – ‘I think this makes it clear that the board is a positive force, not a negative one. Even the “I hate So-and-So” cards are useful: they identify the students whom we need to watch for signs of bullying, in one direction or the other. This is our window into the students’ private world, Detectives. If you know anything about young girls, then you’ll understand just how invaluable that is.’

‘Sounds deadly all round,’ said Conway. Tossed the pen again, whipped it out of the air. ‘Did the invaluable board get checked after school finished up yesterday?’

‘After classes end every day. As I told you.’

‘Who checked it yesterday?’

‘You would have to ask the teachers. They decide amongst themselves.’

‘We will. Do the girls know when it’s checked?’

‘I’m sure they’re aware that it is monitored. They see teachers looking at it; we don’t attempt to conceal the fact. We haven’t announced the precise schedule, however, if that is your question.’