‘Thanks.’ I gulp down the water. The lift stops and I go to get out, but Matt pulls me back as two guys about Dad’s age get in. They’re in t-shirts and shorts and one of them has a towel draped around his shoulders.

‘Not here, sis,’ says Matt. The guys don’t even look at us. They’re too busy talking about some banking issue at their work. Matt and I stand silently at the back of the lift as it climbs the last few floors. Finally we reach the forty-ninth floor.

I follow Matt as he follows the two guys. I know Matt’s hoping they’re going to the pool, too, because we need someone to swipe their security pass and let us in, otherwise we’ll be loitering around the heavy metal rooftop door and we’ll look really suss.

We’re in luck. One of the men taps his pass. Matt sticks out his hand to stop the door from closing and we’re through. Sunlight hits my face as we walk out onto the rooftop. The pool is surrounded by a glass-panelled fence and there are white towels piled in a pyramid near the gate.

Matt smiles at me. I sort of smile back, but my legs are wobbly and a rush of something makes me reach out and hold the gate before I fall.

‘Don’t make too much noise or do any bomb dives into the pool. There’s a camera up there and it’ll draw attention to us,’ Matt says, nodding towards it.

I see the camera and imagine my face being watched on a wall of black-and-white TV screens by a burly man with a gun.

Matt holds the gate open for me and I slip through into the pool area. The water is so blue. No-one is swimming. The two guys from the lift are sitting on the white deckchairs, but they aren’t paying attention to us at all. Matt strips down to his board shorts and I think again how weird this all is.

I take off my hoodie, which I wore so nobody could see I was coming into the hotel in my swimming gear. I’m wearing Bridge’s old bathers and a pink-striped rashie so I don’t get sunburnt in seconds. I’ve already covered myself with sunscreen; I didn’t want to do it in front of Matt. But he surprises me by taking out a tube and wiping sunscreen across his face and arms.

Terrified I’m going to be asked to rub sunscreen onto his back, I step down the stairs and into the shallow end of the pool. The water is cool and clear. I kick off the bottom step and out into the middle. Within seconds Matt’s swimming just near me.

‘Float on your back and look up at the sky,’ he says quietly.