'Why not?' I said. 'Am I mad?'

'Is this still to do with the whisky?' said Laura.

I took another sip and shook my head.

'Look at the facts,' I said. 'I break up with Brendan. Next thing, he's engaged to my sister. I can't bear the very sight of him. Next thing, he's living in my flat. Them living in my flat is awful. Next thing, I've moved out. So after days of manoeuvring, the result is that a man who makes me want to throw up when I'm around him is living in my flat and I've become a vagrant.'

'You're living here,' said Laura. 'That's not being a vagrant.'

I put my arms round her and hugged her.

'That's so lovely,' I said, overflowing with emotion.

To an observer we would have looked like two drunks outside a pub after closing time.

'I must say, I'm curious,' said Laura.

'What about?'

'This Brendan. You make him sound so appalling that I'd actually quite like to see him. It's like one of those exhibits in an old circus. Do you dare see the bearded lady?'

'You think I'm exaggerating.'

'I want to see him in action,' Laura said with a laugh. 'I want to see what it takes to make you vomit.'

The next day I was at work early, wanting to give Tony and Laura a bit of time together. I went back to the Hampstead house because the owners kept changing their minds about what they wanted. They'd decided that all the lights in the living room were wrong – they didn't want side-lights after all, but soft halogen spotlights on the ceiling. The Venetian red in the bedroom was too dark; in fact, it was too red. Maybe they should have gone for the pea green colour after all… The man of the household, a Sam Broughton, had arranged to come back to the house at lunch to discuss the fine details, and I spent the morning painting doors and skirting boards, laying licks of glossy white over greying wood.

Sam Broughton had just arrived from the City, insistent that he only had twenty minutes to spare, if that, and we were walking through the house, me with my notepad, when my mobile rang.

'Sorry,' I said to him. 'I'll turn it off after this. Hello?'

'Miranda? Thank God you're there.'

'I'm just in the middle of a meeting, Mum. Could you call back in a…'

'I wouldn't have called except it's an emergency.'

I turned away from Broughton's impatient face, his overdone glances at his watch, and looked out of the window at a sodden squirrel immobile on the branch of a chestnut tree outside. 'Tell me.'

'I've just had a phone call from Troy 's tutor and she says that Troy 's not come in.'

'That's not really an emergency, Mum.'

'He's not come in for days.' She paused. 'Most of last week.'

'That's not good.'

'It's like before. Pretending he's going there and then not turning up. I thought he was getting better.' I heard her gulp. 'I'm worried, Miranda. I called our house and he's not there, or at least there's no reply, and I don't know where he is or what he's doing and it's cold and raining outside.' Another gulp.

'What do you want me to do?'

'I'm stuck here at work. I can't really get away – and, anyway, the dental surgery's miles away. I tried your flat, but there was just an answering machine. So I thought you could just pop over and see if you could find him.'

'Find him?'

Behind me, Broughton cleared his throat angrily. His polished brogue tap-tapped on the newly varnished floorboards.

'It's much easier for you to get away and Bill wouldn't mind. And if something's happened

'I'll see if I can find him,' I said.

'I can't bear all of this any more,' said my mother. 'I've had enough of being strong. It's too much for me. What's wrong with us? I thought it was all going to be all right.'

'It will be all right,' I said, too loudly. 'I'll go now.'

I ended the call and turned to Broughton.

'I have to leave,' I said.

His glare deepened.

'Do you realize how expensive my time is?' he said.

'I'm very sorry,' I repeated. I wanted to say that my time was valuable as well, to me, at least. But I didn't. I was thinking of Troy, out there in the rain.

I went to my parents' house first. The workmen weren't there, though the ground floor looked like a building site – well, it was a building site. The kitchen was half-exposed to the weather. There was yellow London clay everywhere. I went from room to room, calling him. In his bedroom I opened the curtains and shook out the crumpled duvet, to make it look more welcoming if he returned. A book about the migration of birds lay open on the floor. I marked it with a scrap of paper and put it on his pillow.

I didn't really know where to look. Where would I go, if I were him, and hanging around waiting for the end of the day? I walked on to the high street and peered into cafes, record shops, the local bookstore. I tried the library, but it was closed; it's only open two days a week now. I looked into the mini-arcade, where several boys – other truants, I assumed – were playing the fruit machines in the smoky, bleeping gloom. Troy hated places like that. They made him feel trapped.

I walked to the park and wandered around in the rain. There weren't many other people, just a couple of winos sitting on a bench and a young mother striding furiously past pushing a buggy. From its inside came a yell like a siren. No Troy. I went to the playground in case he was taking shelter there, but it was deserted. Pigeons hopped through the puddles. I went to the little snack bar which sells ice creams on sunny days, but there was just one woman in there.

Really, he could be anywhere. I rang Mum at work and she'd heard nothing. I rang Dad, who was in Sheffield on business, but his voice kept breaking up until it eventually crackled into silence. I rang my flat in case Troy had somehow found his way there, but after two rings the answering machine clicked on and my own voice told me no one was there to take the call. I left a message anyway, one of those that go: ' Troy? Troy? Are you there? Can you hear me? If you can hear me, pick up the phone. Please, pick up the phone. Troy?' I heard the note of fear in my voice.

When you're looking for someone, you see them everywhere. Out of the corner of your eye, and then you turn and it's an old man. In the distance, but as they get closer it's nothing like them after all. Ahead of you, and they turn around and it's a stranger's face. I walked for an hour, telling myself reasonably enough that I shouldn't worry too much. In the end, wet and chilly, I went back to collect my car from outside my parents' house and, on the chance that he'd returned, went in.

The hall doorway was slightly open and through it I could see Troy seated on the old sofa. His hair was plastered to his skull, and he was draped in a thick tartan blanket, under which he was naked. He looked so shrunken and desolate, sitting there, that I could hardly bear to approach him. He lifted his head and looked up and gave a half-smile at someone I couldn't see, and a figure moved across to block him from my view. I pushed the door fully open and stepped into the room.

' Troy,' I said. 'Brendan. What's going on?'

I don't know what I was thinking, but my voice was sharp. I pushed past Brendan and knelt by Troy, clutched him by his narrow shoulders.

' Troy? Are you all right?'

He didn't reply, just looked at me, through me. He had the appearance of one of those people you see on the news, who's just been pulled out of wreckage, off a sinking ship.

'Sweetheart,' I said as if he were a baby still. I wanted to cry. 'What happened?'

'I've run your bath,' said Brendan. 'Nice and warm. And I'll bring you hot chocolate while you're in it. OK, mate?'

Troy nodded.

'And I better ring your mum, all right?'

'I'll take you up to your bath,' I said.