It’s gone midnight. She’s been in the interview room for almost two hours. I feel like I’m close to a confession now and I can only hope that Woods senses this too and doesn’t call a halt to proceedings. I just need a little more time: the one thing I’m running out of. And yet I can hear Dr Magnesson’s words echoing around my brain, ‘psychopaths and serial killers rarely, if ever, confess to their crimes because the truth is they don’t see them as such.’

‘Where is George?’ I ask her again. ‘The baby, Rebecca, where is he? What have you done with him? It’s been, what?’ I look at my watch and then at her.

Her face has a yellow tinge to it. Perhaps it’s just the light, but her eyes appear sunken in their sockets like she’s aged ten years in two hours, her pupils are as small as pinpricks and an oily sheen of sweat covers her cheeks and forehead. Her arms are folded protectively across her waist.

‘What is your first childhood memory, Daniel?’ Her voice is raspy and shallow. She’s tired. Tired is good. Tired is usually the prelude to a confession. It’s often a battle of wills, the interview process, a process of gradually wearing someone down until they’re exhausted and backed so far into a corner the only way out is to cough it all up. But Rebecca Harper is a woman who has spent her entire life in a corner, conditioned to unspeakable torture. But she knows the game is up, that it’s over, or at least the part where she gets to kill people is. Only she’s still the one in control, and she knows it. She may be looking at a life stretch behind the door but she still holds the key to the little boy’s whereabouts and safety; she still has the upper hand.

‘Choking on a sweet at school,’ I say, ‘I almost died.’

She looks intrigued.

‘My cousin gave me a boiled sweet, one of those big old-fashioned humbug ones. I put it in my mouth and somehow swallowed it whole. It got lodged inside my oesophagus and I began choking, coughing and spluttering, you know, I couldn’t breathe and I remember the panic I felt – pure icy-cold terror.’

‘What happened?’ Her eyes glint a little, interested in the outcome.

‘A quick-thinking teacher slapped me hard on the back a few times until it flew out of my mouth… I’ll never forget it.’

‘How old were you?’

‘I don’t know, four years old maybe.’

She smiles. ‘You could’ve died, Daniel. Death by humbug – I might never have known you…’ Her voice trails off, like she’s suddenly lost her train of thought.

‘Guess it wasn’t my time.’

‘Time…’ she says, ‘the bad news is that it flies.’

‘And what’s the good news?’ I ask.

‘That you’re the pilot.’

Touché. Well, I’m flying right now alright, by the seat of my pants – and with no working parachute. ‘Why did you kill Nigel Baxter and Karen Walker, Rebecca? Baxter was besotted by you, he paid you for sex, bought you gifts, he never harmed you, or abused you did he? And Karen, she trusted you, thought of you as a friend, said you were like “the daughter she never had”. So why kill them, either of them?’

She’s silent for what feels like a very long time. ‘Nigel was a sad, pathetic spineless man, a pervert who betrayed his wife and got his kicks from prostitutes and watching other people fucking each other.’

‘Hardly warrants poisoning him and slitting his wrists does it? Betraying your wife and indulging in a kinky perversion with other consenting adults? At worst it’s unsavoury, disloyal.’

‘Kizzy was a pathetic wretch,’ she says, ‘destined for a life of misery, much like myself really. No matter how much she tried, no matter what she did to try and improve herself or her situation, she would’ve continually lurched from one disaster to the next.’

‘Even if this was so, it doesn’t give you the right to play God, to decide who gets to live or die, Rebecca.’ I’m careful to keep my tone even, as void of emotion as possible.

‘Some of us are destined for a life of pain Daniel,’ she says poignantly, as though I am included in this statement.

I’m worried she might be right, that she senses this within me, that she thinks of me as a kindred spirit in this respect, but I don’t let it show. And I’m getting worried, like, seriously concerned, about her well-being. She’s shaking almost uncontrollably now, sweating profusely and her skin has changed from yellow to a deathly grey colour and I suggest that I call a doctor again. Then it hits me, hits me like a sucker punch in the guts. She went to the bathroom in the restaurant… she could’ve taken something.

‘Oh Jesus, Jesus, Rebecca,’ I say the words over again as I rush over to her, seizing her by the shoulders. ‘What have you taken? What have you done?’

She starts to vomit, as though on cue, violently spilling the contents of her stomach out onto the table and over the photographs, retching and convulsing in spasms as her slight body tries desperately to rid itself of whatever toxic substance she’s put in it. She attempts to stand but I crouch down on my knees and hold her in the chair, tell her not to move, explain that help is on its way. She feels floppy within my grip, spittle leaving a long thin trail from one corner of her mouth and her head is wobbling on her neck, like it could be knocked off with a gentle push. I feel a rush of horror as I press the panic button, immediately alerting the two officers outside. I shout at them to get an ambulance and call for emergency medical assistance. I’m screaming at them like they can’t hear me, the shock on their faces lingering for a nano-second longer than I can afford.

‘Hurry up,’ I shout. I can feel her slipping in and out of consciousness in my arms and so I pick her up, hold her across my lap and tell her to stay with me.

‘My first memory…’ she struggles to speak, so I put the plastic cup of water to her lips and tell her to drink it, my heart is knocking violently against my ribs, my hands shaking almost as violently as her own. It spills out onto her dress, leaving dark stains.

Davis rushes into the interview room, she’s clutching a piece of paper and she’s about to tell me something, the words struggling to escape her lips. I expect Woods to follow but he doesn’t. A mask of horror fixes itself across her face as she looks at the scene.

‘Jesus Christ, Boss. What the fuck’s happened…? Listen, I’ve got something—’ she holds the piece of paper up like trophy.

‘Not now, Davis!’ my voice is even louder than I expect, more of a scream really. ‘I think she’s ingested poison… She needs help – we need help, now!’

And I know she’s thinking what I’m thinking, that if Rebecca Davis dies then so does baby George – and my career with them both.

‘Rebecca,’ I say, grabbing her chin between my thumb and forefinger, ‘what have you taken? Tell me… what have you swallowed?’

‘… Mummy,’ she says, her eyes are half closed, the stench of vomit hits me and I swallow back the bile that is rising through my gullet. ‘Read me the story again… the story of the three bears, the one where Goldilocks breaks into the cottage and eats their porridge… It’s my favourite… one last time Mummy, read it to me one last time…’

And in that moment it all makes some kind of sense, her memory of her mother reading her a bedtime story as a child before her life became a waking nightmare. It’s the only happy memory she owns.

Davis hesitates for a second and I’m not sure why. She hands me the note and tries to speak, ‘Get out!’ I bark at her, causing a flash of terror to flicker across her features. ‘For fuck’s sake be quick.’ And she turns and runs.

Rebecca’s organs are shutting down. I think she’s swallowed arsenic. I’m furious with Davis for the interruption, probably at Woods’ request. Hell, I’m furious full stop. I pick up the note. It had better be bloody important is all I can think, we’ve got a suspect potentially dying on us and… I open the note and read Davis’ unruly scrawl.

‘Baby George found safe and well. He’s in St Thomas’s being checked over but looks as though he’ll be okay. His mother is with him now.’

I re-read it. I can’t be sure but I think I might be crying because my face feels wet with relief, maybe it’s the water. ‘Rebecca… Rebecca…’ I shake her like a rag doll and she vomits again, violently, involuntarily, spewing her guts over herself and into my lap, it’s hard to keep a grip on her, she’s like mercury in my fingers, her body almost folding beneath itself, slipping from my grasp. I’m about to tell her that we’ve had news that George has been found, that the game is over and he’s safe but I stop myself. She’s trying to speak, to tell me something and I think I know what.

‘The baby… George,’ Rebecca’s voice is barely audible, crackly and laboured like that of an asthmatic old woman, ‘the address is in my handbag, King’s Hall Road, Beckenham. That’s where you’ll find him.’

I nod and reach for it, screwing up the note in my fist and letting it drop to the floor.

‘Thank you,’ I say to her, ‘thank you.’