There was a hand over Kelly’s mouth. She could feel it pressing down on her face; taste the sweat on the fingers slipping between her lips. A heavy weight shifted on top of her and a knee forced her legs apart. She tried to scream but the sound stayed in her throat, filling her chest with panic. She tried to remember her police training – the self-defence moves they’d been taught – but her mind was blank and her body frozen.

The hand slid away, but the reprieve was momentary. It was replaced by a mouth; a tongue forcing its way inside her.

She heard his breath – heavy, excited – and a rhythmic knocking.

‘Kelly.’

The knocking intensified.

‘Kelly. Are you okay?’

The bedroom door opened and the weight moved from her chest. Kelly took a great gulp of air.

‘You were having another one.’

Kelly fought to get her breath under control. It was dark in her room; the shadow in the open doorway backlit by the light in the hall. ‘What time is it?’

‘Half past two.’

‘God, I’m sorry. Did I wake you?’

‘I’m just in off lates. You okay now?’

‘Yes. Thank you.’

The door closed and Kelly lay in the dark, sweat running between her breasts. It had been ten years since she had sat holding Lexi’s hand, listening to her tell the police officer what had happened, then – later – watched her sister through a television screen, as her statement was videoed. Watched her twin sister cry as she recounted every little detail; every humiliating, painful detail.

‘I don’t want Mum and Dad hearing all this,’ Lexi had said.

Kelly had asked her once, years later, if she ever had nightmares. She’d said it casually, as though she’d only just thought about it. As though Kelly didn’t wake with the weight of a man on her chest; with his fingers inside her.

‘Once,’ Lexi had said. ‘A few days after it happened. But never again.’

Kelly’s pillow was drenched in sweat. She threw it on to the floor and rested her head on the sheet beneath. She was off work today. She’d go and see Lexi; maybe have supper with the boys. But first, there was something she had to do.

The London Gazette’s offices were in Shepherd’s Bush, in a huge but unprepossessing building housing several other newspapers. Kelly showed her warrant card to the receptionist then waited on an upright armchair far less comfortable than it looked. She ignored the knot of anxiety in her stomach: so she was working on an investigation in her spare time – it wasn’t an offence to do unpaid overtime.

Even in her head it didn’t sound convincing. Cathy Tanning’s bag dip was no longer hers to investigate, and Kelly should have reported this new development to the sergeant on the Dip Squad as soon as it came in.

And she would, as soon as she had something concrete to report. But the Dip Squad was as strapped for resources as any other department. With nothing concrete to go on, Cathy’s case might not be looked at for days. Someone had to make her a priority.

Three months before Lexi was attacked, she had gone to the police for advice. Someone had left flowers outside her room in student halls; there were notes in her pigeonhole that made reference to what she’d been wearing the previous evening.

‘Sounds as though you’ve got yourself an admirer,’ the desk officer had said. It was making her feel uncomfortable, Lexi had told him. She was too scared to have the curtains open in her room, in case someone was watching.

When her personal belongings went missing from her room, they sent someone out. Recorded a burglary. Could Lexi be certain she’d locked the door? There was no sign of forced entry. What made Lexi think it was the same person who left the notes; the flowers? There was no evidence to suggest they were connected.

A week later, when she walked home from a late lecture and heard footsteps too measured, too close to be accidental, she didn’t report it. What would be the point?

When it happened again, the following week, she knew she would have to go to the police. When the hairs on her arms prickled, and her breath caught in her throat from the fear that grew in her chest, she knew she wasn’t imagining it. She was being stalked.

But it was too late. He’d already caught up with her.

Kelly thought of all the crime prevention initiatives she’d seen rolled out over her nine years in the job. Poster campaigns, leaflet drops, attack alarms, education programmes … Yet it was far simpler than that; they just had to listen to victims. Believe them.

‘Detective Constable Swift?’ A woman was walking towards her, her head tilted to one side. Kelly didn’t correct her. She was in plain clothes; DC was a fair enough assumption. ‘I’m Tamir Barron, I head up the advertising team here. Would you like to come on up?’

The walls of the sixth floor were lined with advertisements from the last hundred years, framed in thick oak. Kelly spotted adverts for Pear’s soap, Brylcreem and Sunny Delight, as Tamir swept her along the carpeted corridor to her office.

‘I’ve got the results of the enquiry you sent through,’ she said, as soon as they were seated, ‘although I still don’t see the connection to – what was it you said you were investigating? A robbery?’

There had been no violence, which meant the theft of Cathy’s keys was a theft, not a robbery, but Kelly decided to gloss over that fact, in case the severity of the crime was directly proportionate to Tamir’s level of cooperation. Besides, if Cathy was right and the offender had followed her home, and had since been using her key to gain access to her house, there was something far more serious going on. A shudder ran through Kelly at the thought of someone creeping around Cathy’s house. What had he been doing? Touching her make-up? Taking her underwear? Cathy had said she thought someone had been in her house when she was at work, but what if that wasn’t the only time? Kelly imagined an intruder moving quietly around Cathy’s kitchen in the dead of night; creeping upstairs to stand by her bed and watch her sleep.

‘The victim was on the Central line at the time,’ Kelly told Tamir. ‘The offender made off with her house keys, and we believe he has since used them to gain access to her property. The victim’s photograph appeared in the classifieds section of your newspaper two days prior to the incident.’ She hoped Cathy had now changed the lock on her back door. Would that be enough to make her feel safe? Kelly wasn’t so sure.

‘I see. There’s just a small issue.’ Tamir was still smiling, but her eyes flicked down at her desk and she shifted slightly in her chair. ‘There’s a certain amount of protocol that needs to be followed in the case of chatlines: companies have to be licensed, and when they advertise they have to provide the advertiser – us, in this case – with their licence number. To be perfectly frank we don’t go after chatline advertisers. You’ll have seen the section is quite small. They’re what I’d call a necessary evil.’

‘Why necessary?’ Kelly said.

Tamir looked at her as though the answer was obvious. ‘They pay well. Most of that sort of advertising – sex lines, escorts, dating agencies and so on – is all online nowadays, but our print readership is still high, and advertising is what pays for it all. As you can imagine, the sex industry is open to all kinds of abuse, so our measures make sure any chatline operators are properly licensed and therefore regulated.’ She looked down at her desk again.

‘But these protocols weren’t followed in this case?’

‘I’m afraid not. The client first approached us at the end of September, with adverts to run daily throughout October. Shortly before the end of the month they submitted a second batch of adverts, and they did the same for November. The account was handled by a new member of staff, a man called Ben Clarke, and he processed the order without a licence number.’

‘That’s not allowed?’

‘Absolutely not.’

‘Can I speak to Ben?’

‘I’ll get his details from HR. He left a couple of weeks ago – I’m afraid we have a rather high turnover of staff here.’

‘How did the client pay?’ Kelly said.

Tamir consulted the notes written on her pad. ‘By credit card. We can let you have those details, and the address of the client too, of course, but I’ll need a data protection waiver from your side.’

‘Of course.’ Damn. Tamir Barron had agreed to see Kelly so readily, she had been holding out hope that the other woman would simply hand over the file. A data protection waiver would need an inspector’s signature, which Kelly wouldn’t be able to get without coming clean about her extra-curricular investigations. ‘In the meantime, perhaps you could let me have copies of the adverts; both those you’ve run, and those waiting to run?’ She held Tamir’s gaze as confidently as she could.

‘A data protection waiver—’ she started.

‘Is necessary for personal details such as addresses and credit cards. I quite understand. But there are no personal details in those adverts, are there? And we are talking about a potential crime series.’ Kelly’s heart banged in her chest so loudly she was surprised Tamir couldn’t hear it. Did she need a data protection waiver for the adverts too? She couldn’t remember, and she mentally crossed her fingers that Tamir wouldn’t know either.

‘A series? Have there been other robberies?’

‘I can’t tell you anything else, I’m afraid.’ Data protection, Kelly wanted to add.

There was a pause.

‘I’ll get copies made of the adverts and have them sent down to reception. You can wait for them there.’

‘Thank you.’

‘Needless to say we’ve spoken to all our staff about the importance of adhering to procedure.’

‘Thank you. You’ll cancel the remaining adverts, I presume?’

‘Cancel them?’

‘The adverts that haven’t run yet. You can’t put them in the paper. They could be facilitating crimes against women.’

‘I sympathise, DC Swift, but with the greatest respect, it’s your job to protect the public, not mine. Our job is to print newspapers.’

‘Could you stop for a few days though? Not cancel the adverts altogether, but …’ Kelly tailed off, aware she sounded unprofessional. She needed concrete proof the adverts related to criminal activity. The link between Cathy Tanning’s keys and her advert was clear, but Zoe Walker hadn’t been a victim of crime. It wasn’t enough.

‘I’m afraid not. The client has paid in advance; I’ll need to get permission from my boss before I can cancel the contract. Unless of course you have a court order?’

The expression on Tamir’s face was neutral, but her eyes were hard and Kelly decided not to push it. She mirrored the other woman’s polite smile.

‘I don’t have a court order, no. Not yet.’

No sooner had Kelly pressed the doorbell than she heard the excited shrieks of her nephews, running to greet her. Five-year-old Alfie wore a Spiderman outfit, teamed with a plastic Viking helmet, while his three-year-old brother Fergus ran towards her on podgy bare legs, his T-shirt sporting the Minion figures he adored.

‘What’s this?’ Kelly said, feigning amazement as she looked at Fergus’s lower half. ‘Big-boy pants?’ The boy grinned and lifted his T-shirt to better show off his briefs.

‘Early days,’ Lexi said as she appeared behind the boys. She scooped up Fergus and kissed Kelly in one fluid movement. ‘Watch where you step.’

Lexi and her husband Stuart lived in St Albans, in an area teeming with yummy mummies and their buggies. After leaving Durham, Lexi had done a PGCE course, finding a job teaching history at the local secondary school. She’d met Stuart – the deputy head – there, and they’d been together ever since.

‘Where’s Stu?’

‘Parents’ evening. I did my lot yesterday, thankfully. Right, you two: pyjamas. Go.’

‘But we want to play with Auntie Kelly!’ Alfie moaned. Kelly dropped to her knees and gave him a squeeze.

‘Tell you what: you two go and do your PJs and teeth double quick, and then we’ll have tickle time. Deal?’

‘Deal!’ The boys ran upstairs and Kelly grinned.

‘It’s a doddle, this parenting lark.’

‘You wouldn’t say that if you’d been here about half an hour ago. Melt-down central. Now, the boys have eaten, so I thought we could put them to bed then eat in peace once they’re asleep; I’ve done a mushroom risotto for us.’

‘Sounds perfect.’ Kelly’s phone beeped and she frowned at the screen.

‘Something wrong?’

‘Sorry, it’s work. I just need to reply to this.’ She tapped out a message then looked up to see Lexi’s disapproving face.

‘You’re welded to that thing. That’s the problem with smart phones – it’s like carrying your entire office in your pocket. You can’t ever switch off.’ Lexi refused to buy an iPhone, extolling instead the virtues of her brick-sized Nokia that went three days without a charge.

‘It’s not a nine-to-five job. Not like you lot, with your three p.m. finishes and all summer off.’ Lexi didn’t bite. Kelly read the incoming text message and fired off another reply. She’d been first on scene at a nasty fight on Liverpool Street concourse, tasked with gathering witness details once the trouble-makers had been nicked. An elderly woman had been caught up in the skirmish, and Kelly had subsequently been in touch with her daughter, who had wanted to update her mum on the case.

‘What she really wants is for me to tell her they’re locked up,’ Kelly said, once she’d explained the situation to Lexi. ‘Her daughter says she’s too frightened to go out in case she sees them again.’

‘And are they locked up?’

Kelly shook her head. ‘They’re kids with no form. They’ll get community service or a rap on the knuckles at best. They’re no danger to her, but she doesn’t see it like that.’

‘But surely it’s not your job to counsel her and her daughter? Aren’t there victim support people for this sort of thing?’

Kelly made herself take a deep breath. ‘I don’t tell you how to do your job, Lex …’ she started, and her sister held up both hands.

‘Okay, okay. I’ll keep out of it. But please, for once can you switch off your phone and be my sister, not a cop?’ She looked at Kelly, her eyes beseeching, and Kelly felt a stab of guilt.

‘Sure.’ She was about to put her phone away when the screen flashed with Cathy Tanning’s number. She looked at Lexi. ‘Sorry, it’s—’

‘Work. I get it.’

She didn’t, though, Kelly thought, as she walked into the living room to take Cathy’s call. She never did.