A couple of the lads are hiding cans under their coats and shuffling off, a reflex response to approaching police.

Joel’s body bucks and crashes down a second time.

I hold my breath.

Analysing . . . analysing.

‘We’ve got a pulse,’ one of the ambulance men calls out.

Ant’s eyes widen. ‘He’s gonna be OK?’

It is eighteen minutes past midnight: that’s how long Joel’s brain and body have been deprived of oxygen. Even if his body is responding, the odds are that what I did wasn’t enough.

He stares at me, his face fierce. ‘A pulse means his heart is beating, right?’

The second ambulance crew are setting up kit on the Lawns, like a mini field-hospital. Tim is talking to the police; the officers frown as Ant and I approach.

‘Keep your distance, lad,’ the policeman says.

‘He’s the patient’s best friend,’ Tim tells the female officer. She’s skinny with grey wiry hair under her cap. Her colleague has a huge belly and his face is slick with sweat, as though the walk from the car has been too much for him.

Yet it’s Joel – the fittest kid I know – lying on the cold earth.

The policewoman leads us towards the car, but Tim holds back. I see the determination on his face: I think he’s hoping to cadge a lift in the ambulance.

Let him.

‘Bet this is your first time in the back of a cop car,’ Ant says, as we climb in.

I manage a weak smile: he’s trying to help us forget what I did, what he saw. ‘This definitely wasn’t how I thought tonight would go.’

It feels like years ago I was that girl worrying about whether Tim would kiss me.

‘We’ll follow the ambulance,’ the policewoman says. We look out of the windows, see a group of women tottering by in short fur coats and strappy heels, like a line-up of chorus girls. Behind them, the lights of the Palace Pier blur and that’s when I realize I’m crying. Why?

I’m nothing to Joel. He barely recognizes me, even though we walked the same route home from school for five years. But I still want to be at the hospital when he wakes up.

If he wakes up.

Chapter 4: Tim

People worship heroes, but it’s all down to the amygdala. We think we make rational choices, but it’s this almond of cells, buried deep in the brain, that determines whether we’re courageous or cowardly, if we fight or if we freeze.

So it wasn’t my fault. Right?