Deleena refuses to give me her phone number  -  she never gives it out to people she's just met, even if they are 'fabulously wonderful writers'  -  but she takes mine and promises to call sometime soon. I don't get to sleep until nearly three in the morning, thinking about her, replaying our conversation inside my head.

A ringing phone startles me. The ghost of the girl is in my face when I jerk awake, hissing silently at me. I ignore her and glance quickly at my watch  -  I've been asleep less than half an hour. Sitting up, I grab my cell, shake the worst of the wooziness from my head and answer.

'Did I wake you?' Deleena asks.

'Yes,' I yawn.

'I can call later if you'd like.'

'No,' I say quickly. 'Don't hang up.'

There's a long pause. Finally Deleena says, 'I had a good time tonight.'

'Me too.'

'I hope I didn't come across like a groupie. It was only when I got home that I realized how many questions I'd asked about your books. I wanted to ring and say sorry. I was hoping to catch you before you went to bed.'

'Please,' I chuckle. 'You don't have to apologize for fawning over me.'

'I wouldn't have said I was fawning,' she mutters.

'Well you were,' I smirk.

Running a hand through my hair, I discover a long piece of purple paper stuck to my scalp. Peeling it off, I ask Deleena if she'd like to meet for breakfast or lunch.

'I can't. I start work early, and I only get to do lunch if it's with a client. Every other day I'm stuck at my desk till closing time.'

'I thought you said you worked regular hours.'

'Regularly long,' she laughs. 'How about meeting up around eight?'

'Great. Where?'

'The National Film Theatre? They're showing a season of eighties horror features. I think Killer Party is playing tonight. I know you love slasher flicks, so I thought we could  - '

'What gave you that idea?' I interrupt, then recall that Summer's Shades features a protagonist who is hooked on gory films.

'You don't like horror?' Deleena asks, taken aback.

'Not really, apart from the classics like The Omen, Hellraiser, The Exorcist.'

'But Summer's Shades . . . ?'

'My characters aren't me, Deleena.'

'But it's so convincing. Shades reads like it was written by somebody truly in love with the genre.'

I laugh. 'Trust me, it wasn't!'

'You aren't a horror buff?'

'Uh-uh.'

'Thank heaven for that,' she sighs. 'I can't stand horror films. I love to read nasty stuff but I can't bear to watch it.'

'You only suggested the film to keep me happy?' I ask cockily.

'Don't crow,' she warns. 'You don't know my phone number. If I disconnect and don't call back, you'll be trotting around London on your tod.'

'What's a tod?'

'Don't change the subject,' she snaps.

'OK. Horror films are out. What does that leave?'

She hesitates. 'A meal?'

'Anywhere particular?' She mentions a small restaurant in the West End. I agree to that, then ask, 'And after?'

'Let's wait and see,' she responds. 'Maybe I'll have had enough of you and will want to go home early.'

'Or maybe you'll want to take me home with you,' I whisper cheekily.

A pause. It lengthens. Just when I'm about to ask if she's still there, she whispers back, 'Maybe.' And hangs up.

The next two nights are delicious. We dine by candlelight in snug restaurants, chatting easily, laughing freely. I'm at ease around her, even more so than I am with Joe. I feel like a different, less complicated and reserved person.

Later we go for slow walks around Piccadilly Circus, bustling with young, loud tourists as it always is, no matter what time of the day you visit. The Mall, the wide road running along St James's Park, quiet at night, peaceful, Buck Palace glittering at the end of it like a fairy princess's palace. Through the lovingly maintained expanse of Hyde Park and down by the casually meandering Thames, the green heart and dark blue soul of this grand old dame of a city.

Sometimes we stroll hand in hand, other times with our arms around each other. We talk softly about our past and future, hopes and dreams, disappointments and failures. I don't tell her everything about myself, but I spill more than I have to anyone else recently. Details from my youth, my difficult teens in Detroit, how my parents died (mother of cancer when I was sixteen, father of what I hope was an accidental overdose two years later), some of my marital woes, how few friends I have, what a quiet guy I am.

She works my past out of me effortlessly, charmingly. And I do the same with her, learning of her equally difficult teenage years, the time she spent in rehab, her fractured relationship with her parents, the way she retreated from the world after she split from her husband.

For all our talking and sharing, we don't kiss. At the end of each night I expect her to offer her lips, but she doesn't. A quick peck on the cheek and that's it, she hops into a cab and slips away. I'm confused but pleased  -  it's nice to be on the slow burn. I'm sure there will be kissing and more later, but for the time being I'm content to talk and walk, getting to know her, letting her get to know me.

Joe returns to London. We meet at a cafe in Soho in the early afternoon. We order drinks and sit outside, baking in the severe July sun. Joe looks tired and drawn. His mother pulled through but the doctor told him it's only a matter of weeks before she succumbs to a fatal stroke.

'I knew she was close to the end,' he says, wrapped up tightly even though everybody else is in shorts and T-shirts, 'but to have it confirmed . . . to be taken aside and told . . . ' He shakes his head. The glass trembles in his hand.

'You should have stayed with her.'

'No,' he says, tugging miserably at his beard. 'Two of my sisters have moved in with her and I've got a brother three doors down. I'd be in the way. I might miss the finale, but that's not such a bad thing. I'm not sure I want to see her when . . . when she . . . ' He comes to a halt. I glance down at the plastic table, ashamed to think of how great a time I've been having while Joe's been up north preparing for death. 'My brother told me a good one,' Joe mutters, managing a thin smile.

I groan. Joe loves terrible jokes. I almost tell him not to bother me, but I know he wants to distract himself from thoughts of his mother. 'Go on,' I growl.

'Sunday. Monday. Tuesday. Wednesday. Thursday. Friday. Saturday.' He pauses, then sighs wistfully. 'Those were the days.'

I chuckle despite myself. 'That's one of your worst ever.'

'So why are you laughing?'

'Damned if I know.'

We grin at one another, Joe managing to put the darkness of the last few days behind him for the time being.

'So what have you been up to?' he asks.

'Nothing much,' I lie.

'No developments on the plot front?'

'To be honest, I haven't paid a lot of attention to the book. I was waiting for you to return.' He perks up when he hears that. 'Also, I've been seeing someone.' He waits for me to elaborate. 'A woman.'

He laughs. 'I didn't think it was a man.'

'I met her at the boat party.'

'Shar's?' he interjects excitedly. 'You went?'

'Yes.'

'And you pulled?'

'I did.'

'Artful bastard,' he snorts, looking more like his old self. 'Didn't take you long to muscle in on the action. What's her name?'

'Deleena Emerson. She works for a private bank in the City.'

I tell him a bit about Deleena, our nights together, how she looks in a black dress, a few morsels about her background. Joe smirks like a shark as I describe her long legs, soft hair and sparkling eyes.

'Tasty,' he purrs. 'Does she have a sister?'

'She's an only child.'

'Pity.' He taps the table admonishingly. 'But I'm not impressed with the way you've let it affect your work. I'm all for romance, but it shouldn't interfere with your writing. What happened to your meeting with John Meyher? Did you go?'

'I postponed it in the end. I wanted you be there, given that you were the one who set it up. He said his diary was open and to simply give him a few hours' notice before dropping by.'

Joe wags a finger at me. 'Can't leave you alone for a minute,' he scolds, then digs out his cell phone and slides it across the table. 'Try and arrange something for this afternoon.'

'But you're tired, Joe. Let's wait until  - '

'No waiting,' he insists. 'When I return to work I'll be stuck in that bloody shop for most of the week, repairing toasters and microwave ovens. I've got an excuse not to go in today  -  I'm still on leave  -  but if we don't go and see him now, I'll be too busy to come.'

'OK.' I pick up the phone and dial.

'You know the number off by heart?' Joe asks.

'I have an almost perfect memory for numbers.'

'You're a man of hidden depths,' he grins.

'You have no idea,' I mutter.

Meyher's wife answers and says that her husband's out but will be back in the afternoon. I check their address with her  -  numbers stick in my brain but nothing else  -  and schedule the meeting for four o'clock.

'We're on?' Joe asks as I hand back his cell.

'Four.'

'Excellent.' He drinks up and accompanies me to my hotel, where he steals a nap on the couch while I wash and dress. He's exhausted. I know how he feels. When my mother was dying, I rarely squeezed in more than a few hours of sleep a night. I'd like to leave him slumbering but he'd hate me if I went without him, so I shake him awake, ply him with coffee, then off we set in a cab hailed by the redoubtable Mr Lloyd.

John Meyher lives in Roehampton, a quiet, nicely maintained suburb in south-west London, very different to the city I've been getting to know, with more of a small-town feel. The air is actually halfway breathable out here. I like it. If I was to live in London, I'd choose somewhere like this.

John is pruning in a small garden in front of his house when we arrive. He's a large man, heavy and tall, thinning grey hair. He welcomes us with a warm smile and takes us inside for the obligatory British cup of tea and a lot of talk about spontaneous human combustion. John's an expert. He doesn't give many interviews. Like most SHC theorists, he's had to deal with ridicule and official denial over the years. He says it's worn him down. But when he sees how eager we are to learn, he comes alive and talks quickly and eagerly.

After a brief history lesson and a swift but comprehensive overview of current trains of thought, John shows us photos of SHC victims, large piles of ash sitting on floors in the middle of kitchens, bedrooms or living rooms. In some a stray hand or foot rests nearby, as if sliced off prior to burning. A pipe lies in the middle of one pile, tobacco spilling out of it on to the human remains.

John points out the surrounding areas, drawing our attention to the fact that although some of the walls and floors are spotted with soot, the floorboards aren't burnt through and the furniture stands unharmed.

'Do you know the kind of heat required to reduce a human body to ash?' he asks. 'It's in excess of nine hundred degrees Celsius. In a crematorium they use giant furnaces and pumps to generate the heat. Assuming you could start a fire that intense in an ordinary house, how could it incinerate a living human and do no other damage to the room in which they died?'

'How do officials explain it?' I ask.

'They don't,' John snorts. 'They just ignore it.'

'And you?' I press. 'What do you think happens?'

'They burn from within. Even scientists opposed to the concept of SHC accept that possibility. Internal gases can build up and ignite. But an explosion like that should hurl shreds of the victim about, not just leave the odd cleanly amputated hand or foot. It's like these people generated a pillar of fire that spread from the centre outwards, and the only bits to survive were the limbs outside the pillar's circumference. I don't know how that can happen. Nobody does. It defies all known physical laws.'

I gaze at a photograph where a hand lies next to a mound of ashes. I think about what John has told us. I put it together with what I already had in mind coming into this meeting. And I start to smile.

After our interview with John, we head to a pub  -  the Minotaur  -  and I down a couple of glasses of rum, my tipple of choice. Wine with a meal, beer if I fancy a casual drink, rum when I want to enjoy my liquor. I'm buzzing. John was the last significant link in the chain. With what he told me, I'll soon be ready to write.

Joe waits for me to explain myself. I catch his eye and grin, lifting my third glass of rum in salute. Joe scowls, half amused, half annoyed.

'Sorry,' I chuckle. 'I know I'm acting like an ass, but this ties everything together. I've been picking away at the strands of this story for a year, and today it finally fell fully formed into my lap. I don't have all the twists and turns worked out yet, but the core is there.'

Joe leans forward. 'Can you tell me, or is it still a secret?'

I stare at my hands and collect my thoughts. 'Remember Pierre Vallance telling us how he can convert mental waves into voices?'

'Yeah.'

'If that's true, and if you could convert the waves into images or objects, it would mean reality is subjective. Some people would have the power to change the world with their thoughts  -  as an example, if one of them imagined a unicorn or an alien, they could bring it into being.'

Joe tugs at his beard. 'You think?'

'Why not? If reality can be physically what we make of it, then someone like Vallance  -  but more powerful  -  could play God. Now, let's say a guy with that power drops a match. He panics and imagines himself going up in flames. Only, due to his ability to reshape reality, he doesn't just imagine himself catching fire, he unwittingly makes it  - '

'Actually happen,' Joe interrupts.

'You got it. And because he's panicking, the flames don't act the natural way  -  they do what his fevered imagination tells them to do and burn through him like a pillar of unbelievably hot fire.'

I sit back, more pieces of the novel clicking together as I speak. 'If a person is unaware of their power and accidentally taps into it and burns to death, that's a tragedy. But if someone is aware of what they can do, and uses their talent to target other people . . . Hell, that's murder, prime material for an Ed Sieveking novel.' I raise my glass, finish off the last of my rum, then tell Joe to drink up. 'We can't sit around boozing all day. We've got a book to write!'