I know that we’ll have to leave the island before one o’clock to get to the mainland safely and I check my watch. Eleven-thirty.

‘I’d like to stay here forever,’ I say. ‘Just you and me.’

Then I forget what I was saying, because I undo another button and see that she’s not wearing a bra.

When we go outside later a mist has rolled in and everything’s blurred and strange. We can’t even see the mainland. The keeper’s tractor isn’t in the yard, so he must be away from the island. Vicky and I are alone here. It occurs to me that we should wait until after the tide, when we know it’ll be safe to cross. I feel responsible for her. But she says that her parents are expecting her back and she’ll be in deep trouble if she’s late, so we set out together, hand-in-hand, like a brother and sister in a kid’s fairy story.

The thing about the tide in the Dee is that it’s not predictable. It snakes through the gullies, filling deep channels that can cut off your progress to the mainland. People have drowned because they don’t show the water the proper respect. Just a hundred yards from the island I lose all my sense of direction. I can’t see land at all. The fog is dense and seems to shift like the soft sand under my feet, so I imagine that there are shadowy figures on the shore with us. No sound. Nothing solid to hold onto except Vicky’s hand, and she seems quite confident that she knows the way. I tell myself that she’s been crossing the estuary since she was a baby and she’s a sailor, so she’ll know about wind direction and the sun. But there is no wind and there’s no sun. I stand still and she stops with me. My feet sink into mud. Nearer to the mainland it’s all sand, so I realize that we’ve probably been going in the wrong direction altogether and out towards the open sea. Forty minutes have passed since we left the island and the tide will be well in behind us by now.

‘Come on!’ she yells and she tugs on my hand. It’s as if she’s high or drunk, or she doesn’t care what happens to her. It comes to me that she doesn’t have the sort of perfect home life that I’d imagined for her and that she really doesn’t mind if she lives or dies.

That’s when I hear it. A dog barking. Very distant and it’s coming from behind me. I’m almost faint with relief. Now we have something to head for. ‘This way!’ I shout it so loud that it echoes around us.

But Vicky doesn’t seem to hear. She’s pulling me out towards the mouth of the river. It’s as if she’s flying, like one of the wading birds that swoops over the sandbanks at low tide, leaping the channels and tugging me after her. I let go of her hand. ‘No. It’s this way.’ But she takes no notice and hurries on.