‘Oral overdose?’ I frown. ‘But … that makes no sense.’

‘Exactly,’ Mary Wren says. Through her open window I can hear the sound of a distant train, growing closer. ‘Ex-addict like him? If he wanted to kill himself he’d have injected the stuff, of course he would. But then, like I said, I never did believe that Ambrose would leave those kids of his own accord – it makes no more sense for him to kill himself than run away. I’m not one for gossip –’ she brings out the lie without so much as a blush – ‘so I’ve kept my thoughts to myself. But in my mind, I never thought it was anything else.’

‘Anything else than … what?’ I say, and suddenly my voice is hoarse, sticking in my throat.

Mary smiles at me, a wide smile, showing stained yellow teeth, like tombstones in her mouth. Then she leans closer, her cigarette breath hot and rank against my face and whispers.

‘I never thought it was anything but murder.’

SHE SITS BACK, watching my reaction, seeming almost to enjoy my floundering, and as I scrabble frantically for the right words to say in response to something like that, a thought flashes through my mind – has Mary known the truth all this time?

‘I – I –’

She gives her slow, malicious smile, and then turns to glance up the track. The train is coming closer. It sounds its horn, and the lights at the level crossing blink with a maddening regularity.

My face is stiff with trying not to show my reaction, but I manage to speak.

‘I find that … I find that hard to believe though, don’t you? Why would someone murder Ambrose?’

She shrugs, her huge shoulders rising and falling heavily.

‘You tell me. But it’s easier to believe than the idea of him killing hisself and leaving those kids to fend for themselves. Like I said, he would have walked through fire for them, especially that Kate. Not that she deserved it, little bitch.’

My mouth falls open.

‘What did you say?’

‘I said he’d have walked through fire for his kids,’ she says. She is openly laughing at me. ‘What did you think I said?’

I feel anger flare, and suddenly the suspicions I’ve been having of Kate seem like vile gossip. Am I really going to let rumour and innuendo turn me against one of my oldest friends?

‘You’ve never liked her, have you?’ I say flatly, crossing my arms over my chest. ‘You’d be delighted if she were questioned over this.’

‘Truth be told? I would,’ Mary says.

‘Why?’ It comes out like a plaintive cry, like the voice of the child I used to be. ‘Why do you hate her so much?’

‘I don’t hate her. But she’s no better than she ought to be, the little slut. Nor are the rest of you.’

Little slut? For a moment I’m not sure if I’ve heard right. But I know from her face that I have, and I find my tongue, my voice shaking with anger.

‘What did you call her?’

‘You heard me.’

‘You don’t believe those disgusting rumours about Ambrose, do you? How can you think something like that? He was your friend!’

‘About Ambrose?’ She raises one eyebrow, and her lip curls. ‘Not him. He was trying to stop it. That’s why he was trying to get them away from each other.’

I feel suddenly cold all over. So it’s true. Thea was right. Ambrose was sending Kate away.

‘What – what do you mean? Stop what?’

‘You mean you don’t know?’ She gives a short hacking laugh, quite mirthless, like the bark of a dog. ‘Ha. Your precious friend was sleeping with her own brother. That’s what Ambrose knew, that’s why he was trying to get them away from each other. I went over to the Mill the night he told her, but I could hear her outside the door, before I even knocked. Screaming at him, she was. Throwing things. Calling him names you wouldn’t think a girl of that age would know. Bastard this and heartless cunt that. Please don’t do it, she says, think about what you’re doing. And then, when that doesn’t work, that she’ll make him regret it, a threat to his face, bold as you like. I got out of there as quick as I could and left them to it, hammer and tongs, but I heard that right enough. And then the very next night, he vanishes. You tell me what I should think, Miss Butter-wouldn’t-melt-in-my-mouth. What should I think, when my good friend disappears, and his daughter doesn’t report him missing for weeks, and then his bones surface in a shallow grave? You tell me.’

But I can’t tell her anything. I can’t speak. I can only sit, gasping, and then suddenly blood rushes back into my fingers and I find myself scrabbling for my seat belt, yanking at the door, snatching Freya out of the back seat as the train thunders past, its speed like a scream in my face.

As I slam the car door with shaking hands she leans across, her deep rasping voice carrying easily above the roar of the train.

‘There’s blood on that girl’s hands, and not just sheep’s blood neither.’

‘How –’ I manage, but my throat is stiff and closing, and the words choke me. But Mary doesn’t wait for me to finish. The lights stop flashing and the barriers begin to lift, and even as I stand there, gaping, the car’s engine roars into life jolting across the tracks.

I can’t let it go on … it’s all wrong.

I am still standing there, trying to process what she’s said, when the lights begin to flash again, signalling the southbound train.

I still have time to cross. I could run after Mary, accost her at the station, demand to know what she meant.

But I think I know already.

It’s all wrong.

Or I could catch the next train, just me and Freya. In two hours I could be back in London, safe, forgetting about all of this.

There’s blood on her hands.

Instead I turn the pram around, and I head back. Back to the Tide Mill.

KATE IS OUT when I get back to the Mill, and this time I make sure of it. Shadow’s lead is missing from the peg by the door, but I leave nothing to chance. I check every room, right up to the attic. Kate’s room. Ambrose’s room.

The door is unlocked, and when I push it open, my heart stutters in my chest for it is just like it was when Ambrose was here, barely a paintbrush out of place. It feels like him. It smells like him – a mix of turps and cigarettes and oil paints. Even the throw over the battered divan is the same as I remember, worn blue and white with a faded pattern like floral china. Only now it is fraying at the edges, and even more sun-bleached.

It is when I turn to go that I see it. There, above the desk, is the handwritten sign. You’re never an ex-addict, you’re just an addict who hasn’t had a fix in a while.

Oh, Ambrose.

My throat tightens, and I feel a kind of furious determination flood through me, blotting out my selfish fear. I will find out the truth. And not just for my own self-protection, but to avenge a man that I loved – a man who gave me shelter and comfort and compassion at a time in my life when I needed those things most.

I cannot say that Ambrose was the father I never had, because, unlike Luc, I had a father – just one that was grieving and hurting and fighting his own battles. But Ambrose was the father I needed that year – present, loving, endlessly understanding.

I will always love him for that. And the thought of his death, and my part in it, makes me angry in a way that I have never felt before. Angry enough to ignore the voices in my head telling me to leave, turn round, go back to London. Angry enough to drag Freya back somewhere she may not be completely safe.

I am angry enough not to care about any of that any more.

I am as angry as Luc.

When I’ve finished checking every room, I run back down the rickety stairs, and go to the dresser, praying that Kate hasn’t thought of this and hidden it in my absence.

But she hasn’t.

There, in the drawer where she took it out for me only yesterday, is the sheaf of papers tied with a red string.

I riffle through them, my hands shaking, until I get to the brown envelope, marked Kate.

I take it out. And for the first time in seventeen years, I read Ambrose Atagon’s suicide note.

My darling Kate, it reads, in Ambrose’s characteristic looping hand.