Kelly took out her chewing gum and dropped it into a bin. Having left home early, if she loitered any more she was in danger of being late, and that was hardly going to endear her to Nick Rampello. She took a deep breath, pushed up her chin, and walked briskly to the door she’d stood in front of on Friday, her umbrella doing little to protect her from the drizzle that seemed to be coming at her horizontally.

Wanting to make a good impression on her first day, Kelly had instinctively reached for her suit that morning, before feeling the coldness of an unwelcome memory. She had worn it for her disciplinary hearing; she could still feel the woollen cuffs scratching her wrists as she stood outside the chief’s office, waiting to be called in.

The reminder had made her nauseous. She had taken the suit off the hanger and bundled it into a bin bag to go to the charity shop, wearing instead her striped shirt with a pair of wide grey trousers that were now dark with rainwater where they met her shoes. Even without the sartorial prompt of the suit, Kelly was assaulted by memories, appearing in reverse order, like a film on rewind. Her return to shift; slinking into that first briefing with her cheeks ablaze, the echo of gossip reverberating in the air. Her months away from work; days on end in her room, unwashed and uncaring, waiting for a disciplinary hearing that could have ended her career. The sound of the alarm, signifying a crisis in custody; an urgent need for support. Running feet; not coming to back her up but to pull her off.

There were no images of the assault flashing in her head. There never had been. During her anger management classes Kelly had been encouraged to talk about the incident; to walk her counsellor through what had happened, what had triggered it.

‘I don’t remember,’ she’d explained. One minute she’d been interviewing the prisoner; the next … the custody alarm. She didn’t know what had caused her to lose control so horrifically; she had no memory of it.

‘That’s good though, isn’t it?’ Lexi had said, when she’d come to visit Kelly after a particularly difficult anger management session. ‘It’ll make it easier to move on from it. Forget it even happened.’

Kelly had buried her face in her pillow. It wasn’t easier to move on. It was harder. Because if she didn’t know what had caused her to lose control, how could she be certain it wouldn’t happen again?

She pressed the buzzer for MIT and waited, huddled inside the shallow doorway, out of the rain. A disembodied voice rang out on to the street.

‘Hello?’

‘It’s Kelly Swift. I’m here on secondment to Op FURNISS.’

‘Come on up, Kelly!’

Kelly recognised Lucinda’s voice and her nerves abated a little. This was a clean slate, she reminded herself; a chance to start again, to prove herself without being judged on her past. She took the lift, walking into MIT without any of the hesitation of her previous visit. A nod of recognition from one of the team – Bob, she remembered, just too late to greet him by name – buoyed her mood, and when Lucinda bobbed up from behind her desk, Kelly was reassured further.

‘Welcome to the madhouse.’

‘Thanks – I think. Is the DI around?’

‘He went out for a run.’

‘In this weather?’

‘That’s the DI for you. He’s expecting you, though; Diggers sent an email round yesterday, letting us know.’

Kelly tried to read Lucinda’s expression. ‘How did it go down?’

‘With Nick?’ She laughed. ‘Oh, you know Nick. Well, I guess you don’t. Look, the DI’s great, but he’s not good with authority. If it had been his idea to have a BTP officer on secondment, he’d be all smiles. As it is, Diggers and he don’t exactly see eye to eye, so …’ Lucinda stopped. ‘It’ll be fine. Now, let me show you where you’ll be working.’

At that moment the door opened and DI Rampello came in. He wore shorts and a Gore-Tex T-shirt; a lightweight fluorescent jacket zipped part way up his chest. He pulled his earphones out and balled them up, rolling them into a pair of Lycra gloves. Water dripped on to the floor.

‘What’s it like out?’ Lucinda said casually.

‘Lovely,’ Nick said. ‘Almost tropical.’ He headed for the locker rooms without acknowledging Kelly, who envied Lucinda her easy relationship with the DI.

She had switched on her computer and was looking for the piece of paper with the temporary log-in Lucinda had given her, when Nick returned, a white shirt sticking to his still-damp back, and a rolled-up tie in one hand. He slung his jacket over the chair next to Kelly.

‘I’m not sure whether to be pissed off that you went to the DCI after I’d already said no to this attachment, or to admire your negotiation skills. In the interest of working relationships, I’ll go for the latter.’ He grinned and stuck out his free hand towards her. ‘Welcome on board.’

‘Thank you.’ Kelly felt herself relax.

‘So you’re an old friend of the DCI’s, I hear?’

‘Not a friend, no. He was my DI on the Sexual Offences Unit.’

‘He thinks very highly of you. I understand you got a commendation.’

Nick Rampello had done his homework. The chief constable’s commendation had followed several months of painstaking work tracking down a man indecently exposing himself to schoolchildren. Kelly had taken scores of witness statements, working closely with the Intelligence unit to eliminate known sex offenders and other undesirables on the police radar. Eventually, Kelly had successfully bid to use decoys – a team of undercover surveillance officers deployed to high-risk areas to pose as potential victims – and caught the offender red-handed. She was flattered that Diggers had remembered, and touched that he had smoothed the waters with Nick by singing her praises. The feeling was short-lived.

‘The DCI wants you working with someone else at all times.’ Nothing about his delivery suggested that Nick knew the reason behind Diggers’ condition of Kelly’s secondment, but she wasn’t naive enough to think the two men hadn’t discussed it. She felt her cheeks grow hot and hoped it wasn’t obvious to Nick, and to Lucinda, who was listening with interest. ‘So you can work with me.’

‘With you?’ Kelly had assumed she’d be paired with a DC. Was it Diggers who had decided the DI would need to keep an eye on her, or Nick himself? Was she really that much of a liability?

‘You might as well learn from the best.’ Nick winked at her.

‘Cocky bastard,’ Lucinda said. Nick shrugged in an I can’t help it if I’m brilliant way, and Kelly couldn’t help but smile. Lucinda was right, he was cocky, but at least he could laugh at himself.

‘Have you sponsored me, Luce?’ Nick said, and Kelly realised – not without some relief – that their conversation was over.

‘I gave it to you weeks ago!’

‘That was for the Great North Run. This is for the Great South Run.’ He looked at Lucinda, whose arms were crossed tightly across her chest. ‘Think of the children, Lucinda. Those little orphaned children …’

‘Oh fine! Put me down for a fiver.’

‘Per mile?’ Nick grinned. Lucinda gave him a stern look. ‘Cheers. Right, I need an update. On the face of it there’s nothing to link Tania Beckett and Cathy Tanning apart from the adverts, but I want to know if we’re missing something.’

‘Put the kettle on and break open that secret stash of Hobnobs, and I’ll fill you in at briefing.’

‘What secret stash?’ Nick began, but Lucinda gave him a withering stare.

‘I’m an analyst, Inspector,’ she raised an eyebrow as she stressed his rank, ‘you can’t hide anything from me.’ She returned to her desk, and Kelly risked a smile.

‘If you point me in the direction of the kitchen, I’ll make the tea.’

Nick Rampello looked at her appraisingly. ‘You’ll go far. Out in the lobby, second door on the right.’

By the end of Kelly’s first day she was intimately acquainted with the kettle. Between rounds of tea-and-coffee-making she had read through the case papers and at 5 p.m. she headed to the incident room with Nick and Lucinda, and a smattering of people to whom she had been introduced and whose names she had instantly forgotten. Several free chairs littered the briefing room, but most people were standing, their restlessness a not-particularly subtle message that they had more important things to be getting on with. Nick Rampello was having none of it.

‘Grab a pew and settle in,’ he instructed. ‘I won’t keep you long, but we’re dealing with a complex investigation and I want us all on the same page.’ He looked around the room, waiting until all eyes were on him, before continuing. ‘It’s Tuesday twenty-fourth November and this is a briefing for Operation FURNISS, an investigation into the murder of Tania Beckett, and into related crimes committed against women, namely theft of keys and a suspected burglary of a woman called Cathy Tanning. The link between these crimes relates to adverts placed in the London Gazette featuring the women’s photographs.’ Nick looked for Lucinda. ‘Over to you.’

Lucinda moved to the front of the room. ‘I was tasked with looking at murders from the last four weeks, but I’ve also done some work around sexual assaults, harassments and burglaries where the victims were lone females. For the purposes of this exercise I discounted domestics, but even so, there are quite a few.’ As she was speaking, she inserted a USB drive into the laptop at the front of the room; the connected projector ready and waiting. The first slide showed thumbnail images Kelly recognised as the women from the London Gazette adverts; the results taken from the file Tamir Barron had reluctantly given to Kelly on her visit to their offices. Lucinda clicked through the next four slides, another dizzying mosaic of thumbnails. ‘These women have all been victims of relevant crime during the last month. You’ll see I grouped them according to physical characteristics. Skin colour, then hair colour, then subcategories according to their approximate age. Obviously it’s not an exact science, but it made the next bit slightly easier.’

‘Pairing them up with the adverts?’ The guess came from somewhere behind Kelly.

‘Precisely. I’ve identified four matches, digging deeper into the case files to cross-reference the advert image against other victim photos.’ Lucinda moved the PowerPoint on, briskly summarising each slide in turn. ‘Charlotte Harris. A twenty-six-year-old legal secretary from Luton who works in Moorgate. Attempted sexual assault by an unidentified Asian man.’ To the left of the slide was a photo labelled with the victim’s name; to the right, the corresponding London Gazette advert.

‘Snap,’ Nick said grimly.

‘Emma Davies. Thirty-four-year-old female, sexually assaulted in West Kensington.’

Kelly let out a slow breath.

‘Laura Keen. Twenty-one. Murdered in Turnham Green last week.’

‘That one’s already on our radar,’ Nick interrupted. ‘West MIT flagged it as a possible link to Tania Beckett because of her age.’

‘Not just possible,’ Lucinda said. ‘I’d pin it as a dead cert, if you’ll excuse the pun. Right, last one.’ She flicked to the next slide, which showed a dark-haired woman in her forties. As with the other women, her photo had been laid out next to a copy of her advert in the Gazette. ‘This is an odd one. Ongoing complaints from a Mrs Alexandra Chatham near Hampstead Heath, that someone is breaking into her house when she’s asleep and moving things around. It’s sitting with the Safer Neighbourhood Team at the moment, but there’s been a bit of a question mark over it from the start. Apparently the attending officer wasn’t convinced anything had ever happened, even though Mrs Chatham is adamant someone is coming into her house.’

Lucinda surveyed her board. ‘Then, of course, we have Cathy Tanning – another victim of a possible midnight prowler – and Tania Beckett, our murder victim. Six. So far. I’m still working on it.’

There was silence in the briefing room, as Nick allowed the significance of Lucinda’s update to sink in, then he pointed to Lucinda’s closing slide, on which the six confirmed cases were listed next to their relevant advert. ‘In total, eighty-four adverts have run so far, which means there are seventy-eight women yet to identify, who may or may not have been victims of crime. Copies of these adverts are here,’ Nick indicated a second whiteboard, ‘as well as in your briefing pack.’ There was a shuffling of paper, as everyone immediately began looking through the stapled document they’d been handed on arrival, while Lucinda continued to talk.

‘I’m still working on matching the adverts that have run with crimes against women carried out in our force area, and I’m also in touch with Surrey, Thames Valley, Herts, Essex and Kent, in case there’s anything cross-border that might fit. I’ve found a couple of possibles, but I’d like to wait till I’m certain before muddying the waters with those, if that’s all right, boss?’

‘That’s fine.’

‘You asked me to do some work on the similarities between the victims, and between the crimes committed. I haven’t got a lot for you, I’m afraid. At first glance the crimes are very different, but when you strip out the obvious – the offence itself, the primary MO – the common thread is public transport: all these women were on their way to, or from, work.’

Nick nodded. ‘I want all their journeys mapped. Let’s see if there’s any crossover.’

‘Already on it, boss.’

‘What do we know about the offender?’

‘Offenders,’ Lucinda said, stressing the plural. ‘Charlotte Harris describes a tall Asian man with a distinctive aftershave. She didn’t see his face, but he was smartly dressed, in a pinstripe suit and grey overcoat. Emma Davies, who was sexually assaulted in West Ken, described her assailant as white and significantly overweight. We’ve got very little on the Turnham Green job, but one of the CCTV images shows a tall white man in the vicinity immediately prior to Laura Keen’s murder.’

‘Cathy Tanning’s keys were taken by an Asian man,’ Kelly said. ‘The CCTV doesn’t show his face, but his hands are clearly visible.’

‘Six crimes,’ Nick said, ‘and potentially six different offenders. It doesn’t take a genius to work out that the adverts are a key part of this investigation; our focus will therefore be on identifying who is placing them.’ He moved to stand at the front of the room, and Lucinda clicked on to the next slide, which showed an enlarged version of Zoe Walker’s advert.

‘The adverts have been running since the beginning of October. They appear in the classifieds, on the second to last page, and all in the bottom right-hand corner. None of the photos have been professionally taken.’

‘Zoe Walker rang me yesterday,’ Kelly said. ‘Turns out her photo was taken from Facebook – she sent me the uncropped version. It’s a picture of her and her daughter, Katie, taken at a wedding a few years ago.’

‘I’ll check out Tanning’s and Beckett’s Facebook pages again,’ Lucinda said, pre-empting Nick. ‘There are similarities between all of the photos, in that none of the women are looking directly at the camera.’ As though they didn’t know they were being photographed, Kelly thought.

Nick carried on: ‘Every advert carries this web address.’ He pointed to the top of the screen, where www.findtheone.com was written.

‘A dating agency?’ The woman next to Kelly had been taking copious notes in a spiral-bound notebook. She looked at Nick, her pen poised. A detective on the other side of the room was looking at his phone, glancing up at the screen to double-check the URL.

‘Possibly. None of the victims recognise the name. Cathy Tanning was a member of Elite for a while, and we’re in touch with them to see if their systems have been compromised. Tania Beckett’s fiancé unsurprisingly insists she’s never been near a dating site, and Zoe Walker says the same. As some of you have no doubt already discovered, the web address takes you to an empty page, black except for a box asking for a password. Cyber Crime have taken on this aspect of the investigation and I’ll keep you updated on their findings. Okay, I’m conscious of time. Let’s move on.’

‘The phone number,’ Lucinda said. She turned to the whiteboard behind her and underlined a number, written in large red letters: 0809 4 733 968. ‘No trace on our intel systems, and an invalid number, which makes its inclusion on the advert – unless it’s an error – rather pointless.’

Nothing was pointless. That number was there for a reason. Kelly stared at the enlarged London Gazette advert on the screen behind Lucinda. There was a line of text beneath the photo.

The website, yes, but then what? What was the password?

Nick had moved to stand next to Lucinda, issuing actions and impressing upon the team the importance of keeping him updated. Kelly stared at the adverts, wondering what they were missing.

‘At this stage of the investigation we’ve got lots of information coming in, with no clear understanding of how it’s linked,’ Nick was saying. ‘Whoever put these adverts in the Gazette is either announcing their intention to commit a crime, or facilitating the commission of crimes by other offenders.’

Kelly was only half listening, her mind twisting itself into knots. What was the point of an advert without a call to action? Why send potential customers to a website without giving them the means of accessing the site?

She sat up, jolted by a sudden thought. What if the phone number wasn’t a phone number at all, but a password?

She made sure her phone was switched to ‘silent’, opened Safari and typed in the domain name.

The cursor blinked at her. She typed 0809 4 733 968 into the white box and pressed enter.

Kelly suppressed a sigh. She’d been so certain the phone number was the key. Just as she closed down Safari a text message flashed on to the screen.

The abbreviated words and the combinations of letters with numbers would have told her the text was from Lexi, even without seeing her sister’s name. Kelly didn’t know anyone else who still wrote texts as though it were the nineties. She imagined her sister frowning over the tiny screen, patiently holding down each key on her ancient Nokia to cycle through the letters.

0809 4 733 968

A thought began to take shape, and she brought up the keypad on her phone. She looked at the number four; at the letters beneath it.

G. H. I.

Reaching one-handed for her notebook, she flipped it open randomly, flicking the lid off her pen and writing down the letters without taking her eyes off her phone.

There were four letters beneath number seven: P, Q, R, S. Kelly wrote them all down.

Up next, two number threes: the letters D, E and F.

Kelly scribbled furiously, the briefing forgotten as she worked her way through to the last number. She picked up her notebook and scoured the numbers, looking for a pattern, a word.

I.

A space.

S. E. E …

I SEE YOU.

Kelly took a sharp intake of breath. She glanced up to see DI Rampello looking at her, his arms folded.

‘Do you have an update on the investigation you’d like to share with us?’

‘Yes, sir,’ Kelly said. ‘I think I do.’