The sensation of being restrained accelerates my fear, and clawing at my scarf with both hands I scream, muscles tensed, waiting for the feel of hot breath on my neck, hands on my throat but there’s only the sound of cotton ripping. My scarf is caught on the branch of a tree, and I wriggle free and run through the gates, almost crying with relief. I’m nearly home. Turning into my street I unzip my bag and fumble for my keys but I’m shaking so violently they fall from my grasp with a clatter. Behind me there’s a cough. A male cough. And I’m shaking as I scoop up my keys.

The communal door to the flats is always unlocked, and I push it so hard it bangs against the wall and springs back, hitting me on the cheek. I clamp my teeth, biting my tongue.

Swallowing my blood, I take the stairs two at a time, and by the time I reach my door I’m trembling so hard I can’t get the key in the lock. The outer door at the bottom of the stairs slams. Has someone else followed me through it? I struggle with the key again. The bottom stair creaks. Is it the floorboards settling or is someone there? I can’t keep still, jigging up and down as I jab the key forward once more, and this time it slides into the lock. I twist it, there’s a click and I fall through my front door, slamming it behind me.

My legs are no longer willing to support me, and I slump to the hall floor, sitting for the longest time feeling the adrenaline slip away, listening to my own juddering breathing, the strains of rap music from the flat above.

When I feel calmer I stand but my legs still feel shaky, and I wobble towards the kitchen window as though the floor is made of sponge. Outside, the street lamps are shrouded in mist rendering much of the street invisible. There’s nothing to be seen. But that doesn’t mean no one is out there.

The light is dim as I switch it on, but as the energy saving bulb shines brighter and brighter, the photos of Callie Blu-tacked to my walls become clearer. I stand in front of one of Callie I’d pulled from Facebook. She’s kneeling in front of a baby pink rose bush, secateurs in hand. What happened to you? Taking a red felt tip, I add the Prince of Wales to the mind map on the fridge and curve a line connecting it to Sophie. Is the pub significant? It’s like staring at a dot-to-dot picture that doesn’t quite make sense if you miss one of the numbers out.

I plug the mobile phone Sara had given me into the charger I’d bought at the Carphone Warehouse but it still won’t switch on. Sitting at my table I hit the space bar on my laptop to wake up the screen. It’s quiet save the sound of my fingertips clicking on the keyboard. I Google ‘Sophie Valentine’ but I can’t find anything immediately relating to Sophie, and on Facebook there are thousands of people with that name. Instead, I try ‘the Prince of Wales’ pub and its address and dip in and out of articles, the TripAdvisor reviews that would put anyone off visiting and then I find something of interest, an archived news report:

The words I’d overheard at the pub settle like a weight on my chest: ‘You don’t want to leave your kids without a father, do you? Imagine how they’d feel if you had an accident?’

The communal door downstairs slams, and I jump. Was that someone going out or coming in? I wait, curling my fingers into fists. There’s no footsteps on the stairs, no movement from the flat above me. A sense of disquiet washes over me and ever so slowly I stand, lifting my chair rather than pushing it back so it doesn’t make a sound. In the brightness of the kitchen all I can see as I look out of the window is my own worried face reflected back at me.

Uneasy, I return to my laptop and open up another archived newspaper report, dated a few days after the one I’ve just read:

Enlarging the grainy image, I study the man in the photograph. His head is turned slightly to the right as though he’s talking to the man standing behind him who is even more out of focus, but it’s definitely him. The same Neil I’d spoken to earlier. Who is he and how did he know Callie and Sophie were sisters?

There’s a bang, but this time it doesn’t come from downstairs. Somebody has thumped on my front door. My heart leaps into my mouth. I’m not expecting anyone. My world has shrunk so much since my surgery there’s only a handful of people who would call round, and they would all ring first to make sure I’m up to it. The knocking comes again, louder this time. Impatient. I don’t dare move. Can hardly breathe. Holding myself perfectly still I wait but then a horrible thought occurs to me. Did I lock the door? I screw my eyes up, remembering my relief as I burst into my hallway, slumping to the floor clutching my bag and my keys. Shit. I didn’t lock it. I know I didn’t.

There is nothing stopping whoever is out there getting in.