After a fraught drive down the M32 during morning rush hour, followed by almost forty minutes trying to get parked, I make my way on foot up Whiteladies Road, the heat already uncomfortable even though it’s not even 9.30 a.m. It’s Monday, my day off. Pippa works Mondays with Clarissa, one of George’s part-time members of staff who’s also a friend of his and a key holder. I have the sudden thought that maybe it’s Clarissa who’s been stealing from Georgio’s, but then I remember George saying that his friend’s dress was bought on a day when Pippa and I were in the shop, so it couldn’t have been Clarissa who pocketed the cash.

Joe wanted to come to Bristol with me today, but he’s working so I said I’d be fine on my own. The weekend has been quiet with no more scary incidents or letters, but I still feel the threat in the air, looming like an axe about to fall. I can’t imagine that the person responsible for the letters has finally lost interest, given up. This morning is a way for me to try to take back control.

Finally, I reach the café where my appointment with the private investigator is to take place. It’s a traditional greasy spoon-type establishment, a tatty relic squatting between an organic artisan bakery specialising in soda bread and an upmarket vegan restaurant. I’m almost twenty minutes late for our meeting, so I hope he received my apologetic text and hasn’t given up on me.

The front door to the café has been wedged open with a scrap of folded cardboard, presumably to let in the non-existent breeze. I step inside the steaming café, drawing attention from the crowded tables where groups of workmen sit drinking tea and shovelling down late breakfasts. Ignoring their stares, I glance down the length of the plate-glass window. Sitting in the corner, at a table by himself, a medium-built olive-skinned dark-haired man in his thirties leans over a laptop. Spread out before him, various papers, mugs and plates litter the table. I’m assuming this is the PI, as he explained on the phone that this particular corner of the café doubles as his makeshift office.

I wipe a light sheen of sweat from my forehead with the back of my hand and walk over to the man. Hopefully he will prove to be the answer to all my problems.

‘Paul Nasri?’ I ask.

He looks up, smiles and closes his laptop. ‘Lizzy?’

‘Yes.’

‘Call me Nas. Good to meet you.’ His accent is thick Bristolian. Reminds me of Ruby. He gets to his feet and we shake hands. ‘Can I get you something to drink? Have you had any breakfast yet? They do a great full English here.’

‘Just a lemonade or Sprite would be lovely.’

He shouts over to the guy behind the counter to bring us a Sprite and more tea. I sit opposite Nas on a somewhat sticky chair and wait while he tidies all his papers away, stacking them in an untidy pile on his laptop.

‘Sorry I’m a bit late,’ I say. ‘Traffic was scary.’

‘Have you come far?’

‘Malmesbury.’

He gives me a blank look.

‘It’s in Wiltshire,’ I explain.

‘Wiltshire? Okay. So, how did you hear about me?’ he asks.

‘Google,’ I reply. ‘It said you’re ex-police, with lots of experience in all types of situations. Your name came up at the top of the page.’

‘My sister works in search engine optimisation,’ he says. ‘Comes in handy for bringing in the business.’

Our drinks arrive, plonked on the table by a stocky man in an apron. I tear off the ring pull, pour the Sprite into my glass and take several huge gulps. The sugar instantly perks me up.

‘So, why do you need a private investigator then?’ Nas asks.

‘I need you to find someone for me.’

‘Missing person? That’s not always easy, but I’ve got a good track record.’

‘Not a missing person as such.’ I start to worry that maybe stalkers aren’t his area of expertise. I should have explained what I wanted when we spoke on the phone. But he insisted on an initial face-to-face meeting. Said it weeded out the time-wasters. If someone wasn’t serious, they wouldn’t bother to schedule a meeting. Otherwise they’d spend hours picking his brains for free on the phone.

‘Okay,’ he says. ‘Why don’t you explain what the problem is, and I’ll see if I can help.’

I take a breath and launch into the events of the past ten days. Nas doesn’t interrupt, but lets me tell the story in one huge, splurging monologue.

He takes a moment to digest what I’ve said and then inhales deeply. ‘At least it sounds like the police are taking you seriously now. So why come to me? Why not leave it with them to deal with?’

‘Because it’s all so slow. They’re no further along. I mean, they’re helpful, and sympathetic and everything, but until this… stalker shows themselves, the police can’t do anything. And this person isn’t stupid. They haven’t left any prints, or let themselves be caught on CCTV. I’m scared. I need someone on my side twenty-four/seven.’

‘I do sleep, you know.’ He gives me a lopsided grin.

‘I don’t mean twenty-four/seven. Sorry, I’m not explaining myself very well. I just mean, I’d feel more secure if someone was actively trying to find whoever’s doing this.’

‘Look,’ Nas says, leaning back in his chair, ‘I’ll be honest with you. The police are probably better placed to do this kind of work than I am. Plus, they’re local to you. I’m all the way over here in Bristol, and it sounds like the person doing this probably lives in the same town as you.’

‘Really?’ My heart sinks. Ever since I had the idea last week to hire a private investigator, I’ve been placing my hopes on this being the answer. After I called Nasri and he agreed to meet me, I rang the bank and had a loan agreed in principle. I was that convinced he would be able to help me.

‘I could lie to you,’ he says. ‘I could take your cash – which, by the way, would probably have racked up into the thousands – but the chances of me finding this person on the evidence you’ve got… well, they’re slim to none.’

I rest my chin on clasped hands as new waves of disappointment hit me. What a total waste of time. I get to my feet. ‘Okay, well, thanks for being so honest.’ I root around in my purse until I find a couple of pound coins. ‘For the Sprite,’ I say, placing them on the table.

He raises an eyebrow. ‘Thanks. Look, I can see I’ve disappointed you. Why don’t you sit back down a minute?’

I hesitate, then do as he asks.

‘There is something simple you can do which might help.’

I sit up straighter.

‘Do you live in a house or a flat?’ he asks.

‘A house. A little cottage.’

‘Good.’ Nas flicks through his pile of papers and tears a strip off the bottom of one of the sheets. He pulls a pen out of his pocket and starts writing. ‘Here.’ He slides the scrap of paper across the table towards me.

‘What’s this?’ I ask, looking at the words, which don’t seem to make much sense.

‘It’s the make and model of a great little spy cam you can use to try and catch your stalker. You said they’ve delivered letters to your house twice now?’

I nod, suddenly understanding what he’s getting at.

‘Chances are they’ll do it again. Stick the camera in a plant pot underneath a leafy plant, or something. If I was local I’d set it up for you. Make sure the lens is pointing upwards to catch their face. Experiment with angles. Okay?’

I don’t know why I didn’t think of this in the first place. Hope replaces disappointment. ‘That’s a great idea! Thanks so much. Where’s the best place to get one of these cameras?’

‘Online’s cheapest.’

‘What if I wanted to get one today?’

He reaches out to take the scrap of paper and scribbles something else on the back. ‘That’s the name and address of a place I use not far from here. Ask for Reuben and tell him Nas sent you. They’ll give you a good discount.’

‘Thank you so much.’

He shrugs. ‘Didn’t really do a lot.’

‘You did. Do I owe you anything, a consultancy fee or something?’

‘Nah, you’re all right.’

‘Okay. Well, thanks. Is the camera place walkable from here?’

‘Yeah. Take you about ten minutes. Turn left out of the café, keep walking and it’s your fourth turning on the right, off the other side of the main road.’

‘Thank you, Nas.’ I down the rest of my Sprite and leave the café, feeling like I have a real purpose now. Why on earth didn’t I think of putting a camera up before? It’s so obvious now that Nas has mentioned it. But I guess everything is obvious with hindsight.

I find the electronics shop, tucked away down a side street. Nas’s friend Reuben spends about half an hour showing me how to use the camera and how and where to position it. He knocks fifty quid off the asking price and I put it on my credit card, part of me relieved that at least I won’t have to take out a loan for Nas’s PI services.

Leaving the shop, I clutch my carrier bag tightly, thrilled with my new purchase. I’m dying to get back to my car, drive home and set the thing up. I can’t wait to catch whoever it is in the act of posting another letter through my door. My mind flashes forward to me presenting my video evidence to the police and them arresting whoever it is.

The air outside is thick and heavy. I’m betting that slice of blue sky above will be eaten up by thunderclouds soon enough. I make my way back to the main road that’s suddenly heaving with shoppers, workers, people eating and drinking in pavement cafés. Cars and bikes whizz down the wide street as I stand on the kerb, trying to get my bearings. A group of foreign students crowd past me, moving at a snail’s pace, their backpacks bashing into passers-by.

As I wait for a gap in the traffic, I hear the slap, slap of running footsteps growing louder, but they’re on the periphery of my hearing. I’m not paying too much attention until the noise approaches, a heavy thud on the pavement behind me. And then I feel a sudden, shocking push at my back and I’m flying into the road. Into the oncoming traffic.

It’s like a slowed-down movie where the sound is turned down and then suddenly turned up loud. A scream rips through the air. It could be my own, but I’m not sure. And in the distance a flash of auburn hair flying away down the street. It looks like… it looks like Emma. Like my sister Emma. But I mustn’t be thinking straight. I’m still flying, and then falling, falling to the accompaniment of car horns, screeching tyres and screams. More screams.

And then silence.