‘I’m touching myself,’ she said. ‘Stroking my clitoris.’ She let out a long, breathy sigh. ‘Ah, that feels amazing. I’m so wet, Andrew. Why don’t you touch yourself?’

‘I am,’ I whispered. But I was lying.

‘Are you hard?’

‘Rock hard.’

She giggled. ‘I love your hard cock. Why don’t you tell me what you’d like to do with it.’

I was aware of Rachel in the next room. Would she be able to hear? I got up and shut the living room door.

‘What was that?’ Charlie asked, her tone changing.

‘Oh, nothing. I shut the door.’

‘Why? There’s no one there to hear you, is there?’

‘No. It’s just . . . cold. I’m trying to keep the warmth in the room.’

She was quiet for a few seconds. ‘You’ve broken the spell now,’ she said. ‘The mood’s gone.’

‘I’m sorry.’ I was relieved.

Charlie sighed. ‘It’s OK. I’ve got to meet Brenda anyway. Maybe I’ll Skype you later. Then I’ll be able to see you.’

My eyes filled with tears. ‘Sounds good.’

‘All right. I love you.’

‘I love you too.’

I awoke with a stiff neck and fluff in my mouth. I groaned and sat up. My sofa was not designed to be slept on. Charlie hadn’t called me back, just sent me a text at 1 a.m. saying she was drunk and going to sleep.

Rachel stayed for breakfast then told me she was going to head to Cardiff.

‘On your bike?’ I asked.

She grinned. She seemed brighter this morning. ‘How else?’

‘Well, be careful.’

‘Are you relieved there isn’t a gang of bikers parked outside?’

‘Nah, I was hoping they’d turn up so I could take them on. I’ve got a big rolling pin.’

She giggled. ‘They’d be terrified.’

I saw her out. She hesitated on the threshold and, on the spur of the moment, I gave her a hug. She looked like she needed one. Her muscles were so tense that it was like hugging a statue.

‘Thank you so much,’ she said, shielding her mouth. ‘You saved my life.’

‘Slight exaggeration perhaps, but you’re welcome.’

After she’d gone, I retrieved the dead bird from the balcony and stuffed it into the bin, tied up in a carrier bag. I found the list on which I’d written Charlie’s possible crimes from my pocket and stared at it. I needed to get started.

But where was I going to start? The logical place had to be her house. I could meet her housemates, take a look through her stuff, even though this made me feel deeply uncomfortable. I needed an excuse for going round there, but I’d think of one.

The bigger problem was that I didn’t know her address. All I knew was that she lived in Camberwell.