‘Are you sure you did the right thing?’ Lexi said. She hoisted Fergus out of the bath and wrapped him in a towel, before passing him to Kelly (‘make sure you dry between his toes’) and doing the same with Alfie.

‘Yes,’ Kelly said firmly. ‘Zoe Walker had a right to know.’ She sat her nephew on her lap and rubbed his hair vigorously with the towel, making him laugh.

‘Won’t you get into trouble?’

Kelly didn’t say anything. She’d been thinking about it ever since she picked up the phone to Zoe Walker. Unable to get it out of her head, she’d come to Lexi’s in search of distraction, ending up telling her the whole story. ‘There we go, all clean and dry.’ She bent her head close to Fergus’s and inhaled the sweet smell of warm skin and talcum powder. Zoe had been grateful to Kelly for keeping her in the loop, and Kelly had told herself that in itself justified her actions.

‘Do you want to stay tonight? I can make up the sofa bed.’

Kelly loved Lexi’s house. It was an unexciting red-brick semi-detached on an estate filled with cars and wheelie bins, but inside it was warm and cosy; a stark contrast to the bedroom waiting for her in Elephant & Castle. Kelly was sorely tempted.

‘I can’t. I’ve got to meet Zoe Walker in Covent Garden at eight in the morning. I’ll need to catch the last train.’ She had hoped Nick would allow her to meet Zoe on her own, thereby avoiding the risk of the DI finding out about Kelly’s call, but he was insisting on accompanying her. Kelly was relying on Zoe to be discreet.

‘Isn’t it – I don’t know – disobeying a lawful order, or something?’ Lexi said, refusing to let the subject drop.

‘Technically, I suppose.’

‘Technically? Kelly!’

Alfie twisted his head round, surprised by his mother’s sharp tone, and Lexi gave him a reassuring kiss. Dropping her voice a notch, she looked at Kelly. ‘Have you got some sort of death wish? Anyone would think you were actively trying to get the sack.’

‘I was doing the right thing.’

‘No, you were doing what you thought was the right thing. It isn’t always the same, Kelly.’

Zoe had arranged to meet Kelly and Nick in a café called Melissa’s Too in a side street near Covent Garden. Despite the early hour the café was already busy, the smell of bacon sandwiches making Kelly’s stomach rumble. A young girl behind the counter was making takeaway coffees with impressive efficiency, and Zoe was sitting at a table in the window. She looked tired; unwashed hair pulled into a hasty ponytail that contrasted sharply with the sleek French plait of the woman sitting next to her.

‘I’m sure something will come up,’ the woman was saying, as Kelly and Nick arrived. She stood to free up the chair. ‘Try not to worry about it.’

‘We were talking about my partner,’ Zoe said, although neither Kelly nor Nick had asked. ‘He’s been made redundant.’

‘I’m sorry,’ Kelly said. Perhaps that explained the tiredness.

‘This is my friend Melissa. It’s her café.’

Kelly stuck out her hand. ‘PC Kelly Swift.’

‘DI Nick Rampello.’

A flicker of recognition passed across Melissa’s face. ‘Rampello? Where have I seen that name recently?’

Nick smiled politely. ‘I’m not sure. My parents run the family Italian restaurant in Clerkenwell – perhaps you saw it there.’

‘That’s where your new café is, isn’t it?’ Zoe said.

‘That must be it. Now, what can I get you all to drink?’ Melissa tugged a small notepad from the breast pocket of her navy blazer and took their order, insisting on serving them all personally, despite the queue that stretched from the counter to the door.

‘Something happened,’ Zoe said, when Melissa had delivered their coffees.

‘What do you mean?’ Nick sipped his espresso, wincing when it burned his tongue.

‘I was followed. On Monday morning on my way to work. I thought I was being paranoid, but saw him again that evening – I tripped and he grabbed me before I fell in front of a train.’ Kelly and Nick exchanged a glance. ‘I put it down to coincidence, but then the next day he was there again.’

‘Did he speak to you?’ Kelly said.

Zoe nodded. ‘He asked me out for a drink. I said no, of course. I still thought it might have been coincidence, but it wasn’t, was it? He knew exactly which way I was going; he was waiting for me. He must have got my details from the website.’ She glanced at Kelly and flushed, and Kelly willed her not to say any more. She sneaked a sidelong look at Nick, but there was nothing about his demeanour which suggested he suspected anything.

‘Did this man give you a name?’ Kelly said.

‘Luke Friedland. I could describe him for you, if that would help.’

Kelly reached for her briefcase and found the paperwork she needed. ‘I’d like to take a statement, if that’s okay? I want everything you can remember about this man, including the route you were travelling, and any times you can be certain of.’

‘I’m going to organise a personal attack alarm,’ Nick said. ‘You’ll have it with you at all times, and if anything happens you can press it. It’ll be monitored 24/7 by our control room and they’ll be able to pinpoint your location.’

‘Do you think I’m in danger?’

Kelly looked at Nick, who didn’t hesitate.

‘I think you could be.’

‘You told her.’

It wasn’t a question.

They were heading towards Old Gloucester Road, to the address provided for them by the London Gazette; the address of the person responsible for placing the adverts in the classifieds. Nick was driving, spinning the steering wheel to switch lanes with the dexterity that came from years of practice. Kelly could imagine him in uniform, racing down Oxford Street on blues and twos.

‘Yes.’

She jumped as Nick slammed the heel of his palm against the horn as a cyclist cut across in front of him, bowling through a set of red lights.

‘I specifically said you were not to inform Zoe Walker about the developments in this case. Which bit of that was so hard to understand?’

‘I wasn’t comfortable with that decision.’

‘To hell with whether you’re comfortable, Kelly, it wasn’t your call to make.’ They turned right on to Shaftesbury Avenue, an ambulance screaming past in the opposite direction. ‘We’re dealing with a complex and wide-ranging investigation, with multiple offenders, multiple victims and God knows how many witnesses. There are more important matters than the way Zoe Walker feels.’

‘Not to her,’ Kelly said quietly.

They drove in silence. Gradually Nick stopped gripping the wheel as though it were about to fly off, and the pulse Kelly had seen throbbing in the side of his temple began to subside. She wondered if she’d made her point in such a way that Nick was actually reconsidering his decision to keep Zoe in the dark, or whether he was mulling over how best to take her off the investigation and send her back to BTP.

Instead, he simply changed the subject.

‘How come you joined BTP and not the Met?’ he said, when they were on the A40.

‘They weren’t recruiting, and I wanted to stay in London. I’ve got family close by.’

‘A sister, right?’

‘Yes. My twin.’

‘There are two of you? Heaven help us.’ Nick glanced at her and Kelly grinned, less at the joke itself than the olive branch it represented.

‘How about you? Are you a Londoner?’

‘Born and bred. Although I’m second generation Italian. Mum and Dad are Sicilian; they came over when Mum was pregnant with my older brother, and opened a restaurant in Clerkenwell.’

‘Rampello’s,’ Kelly said, remembering the conversation with Melissa.

‘Di preciso.’

‘Do you speak Italian?’

‘No more than your average tourist, much to Mum’s eternal shame.’ Held at green lights while the driver in front worked out which way to turn, Nick gave two short beeps on the horn. ‘My brothers and I had to work in the restaurant at weekends and after school, and she used to yell instructions at us in Italian. I refused point-blank to answer.’

‘Why?’

‘Stubborn, I guess. Plus I knew even then that one of us would have to take over the restaurant when Mum and Dad retired, and I didn’t want to encourage them. Joining the police was all I ever wanted to do.’

‘Your parents weren’t keen?’

‘They cried at my passing out parade. And not with happiness.’

They turned on to Old Gloucester Road, and Kelly brought up Google Maps on her phone to see which end of the road they would find number 27. ‘There’s not much residential housing down here – it must be converted flats.’

‘Or it’s a wild goose chase,’ Nick said grimly, pulling up on double-yellow lines outside a Chinese restaurant. Number 27 was sandwiched between a laundrette and a boarded-up bookies. ‘I think our chances of finding Mr James Stanford here are slim.’

Nick took the car’s logbook from the glovebox and left it prominently on the dashboard, the police crest on the cover usually sufficient to deter traffic wardens.

The door to number 27 was grimy with exhaust fumes. It opened into an empty lobby, its tiled floor cracked and dirty. There was no reception desk, and no internal door or lift, only rows of locked mailboxes covering three of the walls.

‘Are you sure we’ve got the right place?’ Kelly asked.

‘It’s the right place, all right,’ Nick said grimly. ‘We’re just not going to find James Stanford here.’ He pointed to a poster on the door, its edges peeling away from the grubby paintwork.

‘It’s a mail centre. A posh PO box number – nothing more.’ He pulled out his phone and took a photograph of the poster, then scanned the rows of mailboxes, which seemed to be in no discernible order.

‘Here it is.’ Kelly had started at the opposite side of the lobby. ‘James Stanford.’ She tugged the handle hopefully. ‘Locked.’

‘The credit card used to pay for the adverts is registered to this address, too,’ Nick said. ‘Get a data protection waiver to them as soon as we get back, and find out who put the mail forwarding in place. We’re being given the runaround, and I don’t like it.’

The company behind the Old Gloucester Road postal address was surprisingly helpful. Keen to avoid any accusation of wrongdoing and – Kelly suspected – aware they had been less than robust with their own checks, they handed over everything they had on James Stanford without waiting for a data protection waiver.

Stanford had provided copies of a credit card bill and a utility statement, as well as his driving licence, showing him to be a white male born in 1959. All three documents gave an address in Amersham, a town in Buckinghamshire at the end of the Metropolitan line.

‘Bet house prices are steep round here,’ Nick commented, as they drove past a series of huge detached houses, each set behind imposing metal gates.

‘Do you want me to let local CID know?’ Kelly said, picking up her phone to find the number.

Nick shook his head. ‘We’ll be in and out before they know it. Let’s check out the house and make a few discreet enquiries with the neighbours if no one’s home.’

Tudor House, Candlin Street, was not Tudor at all, despite the black-painted beams criss-crossing the exterior. A large, modern build, the house was set in what Kelly estimated to be an acre or so of garden. Nick pulled up in front of the gates and looked for a buzzer, but they swung open automatically.

‘What’s the point of those, then?’ Kelly said.

‘Just for show, aren’t they?’ Nick said. ‘More money than sense.’

The gravel drive crunched beneath the wheels of their car, and Nick looked at the house for signs someone was at home. They parked parallel to a gleaming grey Range Rover, and Nick whistled. ‘Very nice.’

The doorbell had an old-fashioned pull mechanism, at odds with the age of the house, but presumably meant to add to the ye olde feel Kelly supposed had been intended by the mock-Tudor facade. Keeping up with the Joneses, she thought. Long before the jangling of the bell had begun to die away, they heard footsteps behind the large front door. Nick and Kelly both stepped away, putting distance between themselves and whoever they were about to meet. It never did to make assumptions about the way people might behave, even in a house like this.

The door swung open and an attractive woman in her early fifties smiled at them expectantly. She wore a black velvet tracksuit with a pair of slippers. Kelly held out her warrant card and the smile disappeared from the woman’s face.

‘Is someone hurt?’ The woman’s hands flew to her throat, an instinctive reaction Kelly had seen a hundred times. There were some people for whom the mere sight of a uniform prompted fear of discovery, or arrest. This woman wasn’t one of them. For her the police meant an accident, or worse.

‘There’s nothing to worry about,’ Kelly said. ‘We’re just making some enquiries. We’re looking for a Mr James Stanford.’

‘That’s my husband. He’s at work. Is there a problem?’

‘Could we come in?’ Kelly said. The woman hesitated, then stood aside to allow them inside a bright, spacious hall. A neat stack of post lay on a narrow hall table, and Kelly glanced at the top envelope as Mrs Stanford led them into the kitchen.

Mr J. T. Stanford.

Nick’s face was impassive, showing none of the excitement Kelly felt certain must show on her own. Was Stanford running the website from this house?

‘James is a management consultant with Kettering Kline,’ Mrs Stanford said. ‘He’s in London today meeting a new client. He won’t be home till late, I’m afraid. Can I help at all? What’s this about?’

‘We’re investigating a crime series,’ Nick said. Kelly watched the woman’s expression carefully. If James Stanford was their man, did his wife know anything about it? Did she have any idea about the adverts or the website? Kelly noted the photographs displayed on the dresser, all featuring what appeared to be the same young man, at various ages.

‘Our son,’ Mrs Stanford said, catching Kelly looking. ‘What sort of crimes? You surely don’t think James is involved?’

‘We need to eliminate him from our enquiries. It would be a great help if you could answer some questions.’

Mrs Stanford paused, unsure of what to do. Eventually manners won. ‘You’d better sit down. Would you like a cup of tea?’

‘No, thank you. This won’t take long.’

They installed themselves at a large oak table. ‘Mrs Stanford,’ Nick began, ‘you said your husband is a management consultant. Does he have any other businesses?’

‘He’s a director of a couple of charities, but no other businesses, no.’

‘Has he ever been involved in running a dating agency?’

Mrs Stanford looked confused. ‘What do you mean?’

‘Premium-rate numbers,’ Kelly explained. ‘This sort of thing.’ She slid a piece of paper across the table and showed Mrs Stanford a single advert from the London Gazette.

Again, the hand at her throat. ‘No! I mean … God, no. Why would he? I mean, what makes you think he’d …’ She looked wildly between Nick and Kelly. Either she was a superb actress, or she knew nothing about what her husband had been up to. Was that why Stanford had used a mailbox address? Not to hide from the police, but from his wife?

Kelly handed Mrs Stanford the rest of the file she was holding. ‘These documents were used to open a mailbox on Old Gloucester Road three months ago, paid for by your husband’s credit card. The same documents, and the same credit card, paid for the insertion of a number of adverts in a London newspaper.’

‘Adverts,’ Nick said, looking intently at Mrs Stanford, ‘we believe are at the heart of a series of crimes against women.’

Mrs Stanford looked at the document, anxiety written across her face; her hand tugging at her necklace. Nick watched her eyes flick from left to right, the confusion and fear gradually giving way to relief.

‘This is nothing to do with my husband,’ she said, the release of tension making her laugh.

‘James Stanford is your husband, though?’ Kelly said.

‘Oh yes,’ Mrs Stanford said. ‘But this photo’ – she pointed at the photocopied driving licence – ‘that’s not my husband.’