As the liquid puddles on the floor, I decide it has to be said. I see him flinch, as if he knows what’s coming.

‘Tim, about that night—’

‘Please, Kerry. I’ve learned my lesson, it’ll be different next time.’

I stare at him. I have to tread carefully. ‘It’s nothing to be ashamed of. And it doesn’t mean you’re not suited to be a doctor or anything like that. But maybe it’s better we clear it up, especially as we don’t even know if I did it right and whether Joel is going to recover properly—’

His eyes widen. He looks as scared as he did on the Lawns. ‘Mum can’t know,’ he whispers. ‘It’d destroy her if she knew what really happened. That’s the only reason I’ve not explained—’

The bell rings for class.

Like Pavlov’s dogs, we respond as we’ve been trained to. Our conversation can wait.

As we go towards the science block, my wet feet chafe against new leather. After class, I’ll talk to Tim again, before things get even more out of hand. I understand why he doesn’t want people to know. Elaine Palmer isn’t quite the sweet, brave single mother everyone else sees. She will be upset. Angry.

But still, the truth matters more. I did step in. Whether Joel’s rages are permanent or not, if I hadn’t acted, he wouldn’t have stood a chance.

I’ve never seen myself as vain. But perhaps I am, because there’s a part of me that wants people to know it was mousy Kerry who saved the day.

As I squelch into Chemistry, the familiarity of the lab makes me feel normal for the first time in five days. Our classmates are staring at us, but I tell myself it’s because my skirt and legs are drenched.

Mr Sykes emerges from the store cupboard and blinks at us as though he’s spent the last fortnight here guarding the petri dishes and Bunsen burners.

‘Well, here we all are. You will recall that I was sceptical about the idea that the so-called millennium bug would lead to the end of the world. My delight at being proved right is tempered by the fact that rather than picking over a post-Armageddon landscape for scraps, I am fated to spend the morning with you lot, attempting to explain the nucleophilic addition mechanism as it relates to aldehydes.’

He twists his face into something that resembles a smile.

‘However, before we embark on that doomed quest, there is something else.’ He reaches underneath his desk and retrieves an old Marks & Spencer carrier bag: he pulls out a rectangular box and presents it to us as though it’s a momentous breakthrough in organic chemistry. In fact, it’s a battered-looking chocolate yule log.