She finished the letter and then looked up at me, a little expectantly.

‘There’s something else in the envelope,’ I said and she frowned, before looking inside and then pulling out the piece of photo strip.

Her face was impassive as she looked down at it, then back up at me.

‘Why did you go to Cambridge?’ she said again, very quietly.

I got to my feet, suddenly unable to be still a moment longer.

‘Because that man is dead!’ I was shouting now. ‘We should have told the police. And you obviously knew this Liam better than you told me you did!’ I was becoming so het up that I wasn’t even speaking in grammatical sentences now. ‘I don’t think you’ve told me the whole story!’

I reached into my pocket and pulled out the piece of printer paper that was folded there. I had easily found the news story from the Cambridge newspaper that Irene had shown me.

I handed it to her.

‘And I have a strong feeling it has something to do with this.’

Can you imagine what it was like for a mother?

Seeing those small finger-shaped marks in the peanut butter and understanding what they meant?

It was hours later. Anya was tucked up in bed, exhausted after all the excitement then trauma of her party. All the other parents had left shortly after the ambulance took Dylan away. Patrick and I had almost finished clearing up all the mess from the party.

The sight of that little boy’s face – the terrible flushing of his skin and the terror in his eyes as his throat closed over – kept running through my mind. Thank God he got to the hospital in time. I can’t even bear to think about … if he hadn’t.

Anyway, I was desperate for a gin and tonic. The bottle of gin was in the larder, a space used as an overspill area for storage at the back of the kitchen. The peanut butter jar had been put precariously on a shelf near the door, not in its usual space.

But here’s the thing: because I was so worried about any possible contamination, I had locked the larder with the tiny key that we’d never had any reason to use before, just to prevent anyone prowling for any extra snacks that weren’t on the approved list.