I stretch out my arms and legs and float on the surface of the water. As I bob along, my breathing slows and the sick feeling in my stomach starts to disappear. I blink up into the brightness. The glare is harsh, but I can make out the blurry tops of buildings that peep down on us. The sky is huge.

My fingers brush up against something and for a second I fight the water, losing the calmness. But then I realise that it’s just Matt floating past. I like that he doesn’t speak to me, that he doesn’t try to engage me in conversation about how great all this is.

A bunch of grey lumpy clouds putt across the sky and block the sun – my own personal visor. I wonder if anyone is watching us on the monitor or if we are free to float our way around the pool all afternoon. I feel a soft splash of water on my face. I try to stand up, but misjudge the depth of the pool. I’m nowhere near tall enough to reach the bottom and have to tread water. I see Matt grinning at me just before he sends another stream of water over my face. Without thinking, I retaliate, but my splash is an armful and it covers him.

Within seconds, it’s on. Him throwing water my way and me hurling it back. And somewhere in between we forget the two men perched on their deckchairs.

‘Oi!’ The sharp sound stops us. One of the men is standing by the side of the pool, the bottom of his shorts dripping. Matt is facing me, but I can see how angry the man is. Matt rolls his eyes; it’s clear he’s leaving it up to me to smooth things over.

‘Sorry!’ I call out, hoping it’s enough to make him sit back down.

‘Are you old enough to be up here alone?’

I know he’s referring to me, because I look about eight, not nearly thirteen.

‘Yeah. My brother’s sixteen,’ I say without smiling.

The man looks at the back of Matt’s head and then at me. I know he’s trying to work something out.

I can feel my heart pounding so heavily under the water that I’m sure the beats are creating ripples around me. I swim for a second, so I can move my body and settle my heartbeat.

‘The only problem with swimming on a rooftop pool is the other guests,’ whispers Matt as he paddles over to me.

‘Thanks for letting me deal with him,’ I whisper back.

‘Is he still there?’

I glance up quickly. He’s gone back to his conversation, but both men seem to be watching us from where they sit.

‘Yeah.’