‘Just you and your nan, is it?’ He settled himself in a large flowery armchair next to the television, and Chelsea plonked herself reluctantly in between the two cats. She nodded miserably, her eyes flicking to a photograph on the mantelpiece above the gas fire. It was of a beaming couple in swimsuits holding hands on a beach. The woman was curvy and gorgeous, and Patrick found himself hoping that this was how Chelsea – ‘Foxy’ – would one day look, once she grew out of the acne and awkwardness. ‘Your mum and dad?’

‘They were killed two days after that photo was taken. Boating accident in Jamaica when they went home to visit my dad’s mum.’

‘I’m so sorry. How old were you?’

‘Four. Been living here ever since.’

Poor kid, thought Patrick. What people go through. He took out his Moleskine. ‘I understand you didn’t turn up for a job interview you were supposed to have yesterday at the bowling alley in Kingston? Would you mind telling me why not?’

Chelsea immediately looked away, her mouth twisting in shock. ‘Is that why you’re here?’ she said, stroking one of the cats so hard that it wriggled away and stalked off into her bedroom. ‘It’s only a poxy Saturday job! I was ill.’

‘What’s wrong?’ Patrick asked kindly. ‘Are you better now?’ He waited for the fake cough again, but Chelsea just stared at the carpet.

‘Chelsea?’

‘Women’s troubles,’ she said stubbornly.

‘Shame. That would’ve been a nice job for you, wouldn’t it? I hear that you hang out at the Rotunda a lot anyway?’

‘How do you know?’

They seemed to be playing a game of Question Tennis, he thought, batting them back and forth without many answers.

‘I’ve been asking around, trying to find out who was there on Saturday night when Wendy was killed. She was a colleague of mine. You heard about it, right?’

Tears welled in Chelsea’s eyes again.

‘You were there that night, weren’t you, Chelsea?’ he prompted gently. ‘Some of your friends said you were. They said you left with a boy.’

Chelsea sank her head into her hands. She seemed to have lost the ability to speak.

‘Was that your boyfriend?’

‘I’m not allowed boyfriends,’ she whispered, pulling her sleeve down over her hand and wiping her eyes with it.

‘Really? But you’re sixteen, aren’t you?’

She nodded. ‘Almost seventeen. In April.’

‘That doesn’t seem too young to have a boyfriend.’

‘My nan says I am. She says I’m not allowed until I finish A levels in case it interferes with my schoolwork . . . What’s the time?’

Her eyes were fearfully darting towards the door.

Patrick pulled out his phone and looked at the screen. ‘Ten past two.’

‘Oh my days.’ She jumped up and ran over to the window. ‘She’ll be back at quarter to three! You can’t be here!’

‘Chelsea, that’s over half an hour away. Please don’t worry.’ Bloody hell, Patrick thought. She’s petrified of her. ‘Come on, sit down. Why are you so scared of your nan coming back?’

She started to cry in earnest this time. ‘I want to help, I do, but I wasn’t supposed to be there, and if she finds out about the car park, then she’ll kick me out like she did before and I’ll have to go into one of them homeless shelters and it’ll be even worse than living here with her, otherwise I’d have gone myself ages ago—’

Patrick straightened up, every hair on his body standing to attention. ‘The car park? Chelsea, what do you know about the car park? Tell me!’

The girl was almost hysterical. Patrick got up and found a plastic beaker upturned on the draining board in the kitchen. He filled it with water and took it in to her, with a clean tissue from his pocket.

Crouching down next to her, he handed her the water and the tissue.

‘You were there, weren’t you? In the car park? Is that why you didn’t go to your interview yesterday, because you were too scared by what you saw?’

‘What if she finds out?’ the girl wailed.

‘Were you doing something you shouldn’t have been doing? Drugs? I don’t care if you were.’

‘NO! I don’t do that shit.’ Her outrage seemed to help her gather herself. She sniffed mightily, then dabbed under her eyes with the tissue – although, Patrick thought, she’d have been a lot better off wiping her runny nose. Something clicked into place.

‘You were with that boy, weren’t you? It’s OK,’ he reiterated. ‘You aren’t in trouble, not with us. We just need to know.’

‘Nan will kill me!’

Patrick knelt beside her, his knees cracking loudly. ‘She won’t need to know. You’re sixteen. It’s confidential, I promise you.’ Especially because he wasn’t here officially, though Chelsea didn’t need to know that.

She looked up at him then, her face a pulpy mess of snot, smeared make-up and tears.

‘I saw it happen,’ she whispered.

Patrick stopped breathing altogether. The only sound in the room was the gentle purring of the cat.

‘Go on.’

‘Me and – do I have to give his name? I don’t want to.’

The boy’s name would be useful. Another potential witness. But he knew if he insisted Chelsea would clam up again. ‘That’s OK – you and the boy, you were there . . . where?’

‘In the corner of the car park, although he’d gone by then. I just needed a minute to . . . get myself together again. It was dark in that corner and nobody else was there, not when we arrived. We just wanted to be on our own. We, er, you know . . .’ Chelsea’s voice was strangled with embarrassment.

‘Were having sex?’

She nodded, mortified. ‘Promise you won’t tell Nan!’

‘I won’t. It doesn’t matter. All that matters is what you saw.’

She took a sip of the water, her hand shaking. ‘We, um, did it, quite fast, then he had to go otherwise he’d miss his bus.’ Patrick had a flash of Bonnie telling this sordid tale in a decade and a half and shuddered. ‘I didn’t want to run with him, I hate running, so I told him to go without me. Anyway I was a bit – emotional. It was my first time. It wasn’t how I thought it would be.’

Poor kid, Patrick thought again. Her first experience of sex was a shag in a freezing dark car park, the experience topped off by her partner legging it and leaving her to witness a murder. Wendy’s murder.

‘I was about to leave and then I saw this girl come in – well, I thought she was a girl, I didn’t know then that she was a cop. She looked well young, too young to drive, so I thought it was weird she was there. She walked over to the far side – it was dark over there too, the lights were out – and next thing this man comes running in and they didn’t even speak or anything, he just stabs her and runs away and she’s lying on the floor and there’s blood everywhere and I sort of run over and her eyes were open, but then they closed and I could see that she was gone and I did mean to call 999, honest I did, but my phone was dead and I was really scared and I felt sick, so I—’

She collapsed into fresh sobs.

‘Ran away?’ Patrick supplied. He was feeling a bit emotional himself, at the knowledge that he was talking to the last person who had ever seen Wendy alive.

‘I ran away and went home and heard it on the news and haven’t been out since. I never want to go there again. I never want to see Josh again – not that he’s called me anyway. He was only after a shag . . . Nan doesn’t know I go out at night. She cleans in a hotel every weekend till 11 p.m. I’m supposed to be here. I thought if I got a job at the Rotunda, then I’d still be able to hang out there and see my mates, but I don’t want it now . . .’

Josh. So that was his name, thought Patrick. They’d need to speak to him too, although it sounded like he had gone before either Wendy or her assailant arrived. Chelsea was still gabbling, so he put a hand on her arm to stop her.

‘Chelsea, this is the most important bit: what did he look like, the man who stabbed her? Did you recognise him, from the bowling alley, maybe?’