‘Lily is missing, Treen.’

‘A sixteen-year-old girl you barely know, with two parents and at least two grandparents, has buggered off for a few days like she’s done before. Like teenagers sometimes do. And you’re going to use this to throw away the greatest opportunity you’re ever likely to be given? Jeez. You don’t even really want to go, do you?’

‘What the hell is that supposed to mean?’

‘Far easier for you to just stick with that depressing little job and complain about it. Far easier for you to sit tight and not take a risk and make out that everything that happens to you is something you couldn’t help.’

‘I can’t just up and leave while this is going on.’

‘You’re in charge of your own life, Lou. And yet you act like you’re permanently buffeted by events outside your control. What is this – guilt? Is it that you feel you owe Will something? Is it some kind of penance? Giving up your life because you couldn’t save his?’

‘You don’t understand.’

‘No. I understand perfectly. I understand you better than you understand yourself. His daughter is not your responsibility. Do you hear me? None of this is your responsibility. And if you don’t go to New York – an opportunity I can’t even talk about because it makes me want to actually kill you – I’ll never talk to you again. Ever.’

The traffic warden was at my window. I wound it down, pulling the universal face you make when your sister is going off on one at the other end of your phone and you’re really sorry but you can’t cut her short. He tapped his watch and I nodded, reassuringly.

‘That’s it, Lou. Think about it. Lily is not your daughter.’

I was left staring at my phone. I thanked the traffic warden, then wound up my window. And a phrase popped into my head: I’m not his daughter.

I drove around the corner, pulled up beside a petrol station and rifled through the battered old A–Z that lived in the footwell of my car, trying to remember the name of the road Lily had mentioned. Pyemore, Pyecrust, Pyecroft. I traced the distance to St John’s Wood with my finger – would that take fifteen minutes to walk? It had to be the same place.

I used my phone and looked up his surname along with the street name, and there it was. Number fifty-six. My gut tightened with excitement. I started the ignition, wrenched the car into gear and headed out onto the road again.

Although separated by less than a mile, the difference between Lily’s mother’s house and her former stepfather’s could not have been more pronounced. Where the Houghton-Millers’ street was uniformly grand white stucco or red-brick houses, punctuated by yew topiary and large cars that seemingly never got dirty, Martin Steele’s road appeared resolutely un-gentrified, a two-storey corner of London where house prices were spiralling but the exteriors resolutely refused to reflect it.

I drove slowly, past cars under canvas and an overturned wheelie-bin, and finally found a parking space near a small Victorian terraced house of the kind that existed in identikit lines all over London. I gazed at it, noting the peeling paintwork on the front door, the child’s watering-can on the front step. Please let her be here, I prayed. Safe within those walls.

I climbed out of the car, locked it, and walked up to the front step.

Inside I could hear a piano, a fractured chord being repeated again and again, muffled voices. I hesitated, just a moment, and then I pressed the doorbell, hearing the sudden answering stop to the music.

Footsteps in the corridor, and then the door opened. A forty-something man, lumberjack shirt, jeans and day-old stubble, stood there.

‘Yes?’

‘I wondered … is Lily here please?’

‘Lily?’

I smiled, held out a hand. ‘You are Martin Steele, yes?’

He studied me briefly before he answered. ‘I might be. And who are you?’

‘I’m a friend of Lily’s. I – I’ve been trying to get in contact with her and I understand that she might be staying here. Or that perhaps you might know where she is.’

He frowned. ‘Lily? Lily Miller?’

‘Well. Yes.’

He rubbed his hand against his jaw, and glanced behind him towards the hall. ‘Could you wait there a moment, please?’ He walked back down the corridor, and I heard him issuing instructions to whoever was at the piano. As he came back to me, a scale began playing, hesitantly and then with more emphasis.

Martin Steele half closed the door behind him. He dipped his head for a moment, as if he were trying to make sense of what I had asked him. ‘I’m sorry. I’m slightly at a loss here. You’re a friend of Lily Miller’s? And you’ve come here why?’

‘Because Lily said she came here to see you. You are – were – her stepfather?’

‘Not technically, but yes. A long time ago.’

‘And you’re a musician? You used to take her to nursery? But you’re still in contact. She told me how close you still were. How much it irritated her mother.’

Martin squinted at me. ‘Miss –’

‘Clark. Louisa Clark.’

‘Miss Clark. Louisa. I haven’t seen Lily Miller since she was five years old. Tanya thought it would be better for all of us when we split up if we broke off all contact.’

I stared at him. ‘So you’re saying she hasn’t been here?’

He thought for a moment. ‘She came once, a few years ago, but it wasn’t great timing. We’d just had a baby and I was trying to teach and, well, to be honest, I couldn’t work out what she really wanted from me.’

‘So you haven’t seen or spoken to her since then?’

‘Apart from that one very brief occasion, no. Is she okay? Is she in some kind of trouble?’

Inside, the piano kept playing – doh re mi fah soh lah ti doh. Doh ti lah soh fah mi re doh. Up and down.

I waved a hand, already backing away down the steps. ‘No. It’s fine. My mistake. I’m sorry to have bothered you.’

I spent another evening driving around London, ignoring my sister’s calls and the email from Richard Percival that was marked URGENT and PERSONAL. I drove until my eyes were reddened from the glare of lights and I realized I was now going to places I had already been, and I ran out of cash for petrol.

I drove home just after midnight, promising myself I would pick up my bank card, drink a cup of tea, rest my eyes for half an hour, then hit the road again. I took off my shoes and made some toast that I couldn’t eat. Instead I swallowed another two painkillers and lay back on the sofa, my mind racing. What was I missing? There must be some clue. My brain buzzed with exhaustion, my stomach now permanently knotted with anxiety. What streets had I missed? Was there a chance she had gone somewhere other than London?