Anna had barely left the house at all for months. She’d been on strict bed rest before the birth, and then afterwards when we brought Charlotte home, she turned into someone I didn’t recognise. It wasn’t right, and neither was she. Her whole life was suddenly only about our daughter, and nobody could make her see that it was all too much, that she needed to take a step back. If I mentioned getting help, it only made things worse.

I’d arranged for her mother to babysit for one night, just one night, for God’s sake, it was meant to be a kind thing to do. For both of them. But when we went to collect Charlotte the following morning, I knew that something was wrong as soon as Anna’s mother opened the door. She had promised not to drink while looking after the baby, but we could both smell the alcohol on her breath. She didn’t say a word, but looked as though she had been crying. Anna pushed her mother aside, and ran into the house. I was only a few steps behind. The travel cot was exactly where we had left it, Charlotte was still inside, and I remember the relief I felt when I saw her. It was only when Anna lifted her up that I could tell our little girl was dead.

There is no such thing as unconditional love. I didn’t really blame Anna’s mother. She’d only started drinking after discovering Charlotte had stopped breathing in the middle of the night. She’d panicked. For some reason she didn’t call an ambulance, I think perhaps because she already knew the child was dead. The coroner confirmed it was a cot death, and could have happened any time, any place. But I blamed myself. So did Anna. Over and over again, screaming the silent words at me through her never-ending tears.

I loved our little girl just as much as she did, but it felt like Anna was the only one allowed to grieve. Now, two years later, I seem to be teetering on the edge at all times, a domino on the verge of falling over and taking those closest down with me. For a long while after what happened nothing about my life felt real or had any meaning. It’s the reason I left London and came back here. To make some sort of family with what I had left: a sister and a niece. And to give Anna the space she said she needed.

We buried Charlotte in Blackdown – Anna was in no fit state to make a decision at the time, so I made it – and I think it’s something else she still hates me for.

It’s a half-hour walk along pitch-black footpaths and deserted country lanes, from Priya’s end of town to mine, but walking is the only option. There are no cabs in the countryside. No signs of life at all in Blackdown at this time of night. A black cat runs in front of me, crossing my path and contradicting my last thought. It’s the sort of thing that would have worried my ex-wife, but I don’t buy into all that superstitious nonsense. Besides, I’ve already had more than my fair share of bad luck.

It’s bitterly cold, the variety that bites if you dare to stand still in it for too long. So I shove my hands deeper down inside my pockets, and keep them there rather than smoke. Strangely, I don’t even feel the need for a cigarette now, after spending an evening talking to another human being instead of staring at a screen.

Rachel and I didn’t really talk, we just shared polite conversation accompanied by impolite sex. It never felt like we had much to say to each other, at least not things that either of us would have wanted to hear. I keep thinking about the words that were painted on her fingernails: TWO FACED. Anna and I used to talk before Charlotte came along, but it was as though we forgot how. Tonight, with Priya, I felt like a real person again.

I decide to send her a text, and reach inside my pocket for my phone.

I find Rachel’s phone instead, and there is an unread message:

You should have gone straight home tonight, Jack.

I stop walking and stare at the words for a few seconds. Then turn a full three-sixty, peering into the darkness, trying to see whether someone is following me now. Someone clearly has been. I wasn’t imagining it. I shove the phone back into my pocket and walk a little faster.

I can see that my house is in complete darkness when I turn onto the street. Nothing unusual about that; it’s late, and I don’t expect my little sister to wait for me to come home. We’ve never been the kind of siblings to check up on each other. I presume Zoe has had a couple of glasses of cheap wine and gone to bed, just like she does most nights.

I start searching for my keys as soon as I get through the gate, struggling to find them in the gloom. The porch light comes on by the time I am halfway down the garden path, but despite it shedding some light inside my jacket pocket where my keys should be, I can see they aren’t there.

I hate the idea of having to wake the whole house in order to get Zoe to let me in – it can be hard to get my niece to go back to sleep – but when I step up to the front door, I see that won’t be necessary. It’s already open.

There is always a heartbeat-length moment, when you know that something very bad is about to happen, and you are too late to do anything about it. It lasts less than a second and more than a lifetime all at once, while you are frozen in space and time, reluctant to look ahead, but knowing it’s too late to look back. This is one of those moments. I have experienced only a few like it in my life.

I sober up fast.

The police part of my brain tells me to call someone, but I don’t. What is left of my family is inside this house and I can’t wait for backup. I hurry through the front door, switching on the lights in all of the downstairs rooms, finding each one as empty as the last. The rest of the doors and windows appear to be closed and locked. I check the alarm system, but it looks as though someone has turned it off. The only way to do that is by knowing the code.

There is no sign of forced entry, no sign of a struggle; if anything the whole place looks a lot cleaner and tidier than when I left this morning. Toddlers are experts at creating mess, but all the clutter and chaos I’ve grown used to has been tidied away and put back in its place. Everything feels wrong, and I’ve learned over the years to trust my gut about things like this.

That’s when I see it.

One of the smaller knives is missing from the block on the counter. I remember that it wasn’t there this morning either, or the night before. My house keys are here too, even though I’m sure they were in my pocket earlier tonight, before I went to Priya’s home. Maybe I did leave them here – the last few days are a sleep-deprived blur. Then I see the photo. It’s just like the one Anna said was stolen from her car, and it’s a picture that I remember taking twenty years ago.

The five girls are lined up and smiling at the camera: Rachel Hopkins, Helen Wang, Anna, Zoe, and a strange-looking girl I vaguely recognise, but can’t remember her name. They are wearing matching grins on their faces, and matching friendship bracelets on their wrists. But that isn’t all. Three of the five girls in the photo have a black cross drawn over their face now: Rachel, Helen… and Zoe.

I drop the picture – realising too late that I should never have touched it – and run up the stairs two at a time. I reach my niece’s room first, bursting through the door to see that Olivia is safe and sound, tucked up asleep in bed. Her pillow, along with everything else in the room, is covered in a pattern of unicorns. She looks so peaceful that for a moment I think maybe everything is OK. But then I realise that the noise I just made would normally have woken her. Olivia is breathing, but she’s completely out of it.