The interior felt plush, reminding Grace of an old-fashioned gentlemen’s club. It was panelled in dark, glossy wood, there were two black leather armchairs and thick carpet, and a strong smell of furniture polish. Only the glass-fronted cabinets, containing a small selection of very old-looking stamps, and the glass-topped counter, containing a row of coins on purple velvet, indicated it was a business.

As the front door closed behind them, a tall, hugely overweight man of about fifty, with a big welcoming smile on his face, materialized through a concealed door in the panelling. Dressed in keeping with the premises, he was parcelled in a well-cut, chalk-striped three-piece suit and sported a striped college tie. His head was almost completely bald, except for a narrow fringe like a pelmet halfway up his forehead that looked faintly comical, and it was impossible to tell where his triple chin ended and his neck began.

‘Good morning, gentlemen,’ he said affably, in a higher-pitched voice than Grace had expected. ‘I’m Abe Miller. How can I help you today?’

Dennis and Pat showed their shields and introduced Roy Grace. Abe Miller remained completely affable, showing no disappointment that they were not customers.

Grace, thinking the man looked too big and too clumsy to handle items as delicate as rare stamps and coins, showed him the three different photographs of Ronnie Wilson that he had brought. To his excitement he saw a glimmer of recognition in Abe Miller’s face. The dealer took a second look at them, and a third.

‘He was believed to be in New York around the time of 9/11,’ Grace prompted.

‘I’ve seen him.’ He nodded thoughtfully. ‘Let me think.’ Then he raised a finger in the air. ‘You know, I’m pretty sure I remember this guy. Know why?’ He looked at each of the three policemen.

Grace shook his head. ‘No.’

‘Because I think he was the first person to walk in here after 9/11.’

‘His name is Ronald Wilson,’ Grace said. ‘Ronald or Ronnie.’

‘Name doesn’t ring a bell. But let me check something in back. Just give me two minutes.’

He disappeared through the hidden door and returned a minute later holding an old-fashioned index card, with notes on it written in ink.

‘Right here,’ he said. He put the card down and read from it, for a moment. ‘Wednesday 12 September 2001.’ Then he looked up at the three of them again. ‘I bought four stamps from him.’ He continued reading. ‘Each of them an Edward, one pound, unmounted, mint. Perfect gum, no hinge.’ Then he grinned mischievously. ‘Paid him two thousand bucks each. I got a bargain!’ He looked at his card again. ‘Sold ’em on just a few weeks later. Made a good profit. Thing was, he shouldn’t have sold them, not that day. Hell, we all thought maybe the world was going to end.’

Then Abe Miller looked at the card again and frowned.

‘You said Ronald Wilson?’

‘Yes, Grace replied.

‘Nope, no, sir. That was not his name. Not the name he gave me. I wrote down here David Nelson. Yep, that was his name. Mr David Nelson.’

‘Did he give you an address or a phone number?’ Grace asked. ‘No, sir, he did not.’

As soon as they were back out on the street, Grace called Glenn Branson. He told him to get Norman Potting and Nick Nicholl to make it their first priority to find out whether there were immigration records going back to 2001, and if so, whether any David Nelsons show up on them.

He felt good about the meeting he had just had. But the one shadow, as Glenn picked up on, and which he had already thought about, was whether Ronnie Wilson was still using that name if and when he went to Australia. Maybe by then he had become yet another person.

But an hour later, as they were about to enter the slate-blue and grey Medical Examiner’s Office, Glenn Branson phoned, sounding excited. ‘We have a development!’

‘Tell me?’

‘I said earlier that we’d lost Katherine Jennings, right? That she gave the surveillance team the slip. Well, get this. She walked into John Street Police Station an hour ago.’

The words were like an electric shock. ‘What? Why?’

‘She says her mother’s been kidnapped. A sick little old lady. A guy’s threatening to kill her.’

‘Have you spoken to her?’

‘A CID officer spoke to her down there – and discovered the man she is accusing of the kidnap is none other than Chad Skeggs.’

‘Shit!’

‘I thought you’d like it.’

‘So what’s happening now?’

‘I’ve sent Bella, along with a Family Liaison Officer, Linda Buckley, to bring her up here. I’m going to see her with Bella when she gets here.’

‘Call me as soon as you’ve spoken to her.’

‘What time are you flying back?’

‘Leaving at 6 o’clock – that’s 11 o’clock tonight your time.’

Branson’s voice changed suddenly. ‘Old-timer, I might need to crash at your place tonight. Ari’s doing her tank. I didn’t get home until midnight last night.’

‘Tell her you’re a police officer, not a fucking babysitter!’ ‘You tell her. Want me to call her, put her on the line?’ ‘The key’s in the usual place,’ Grace said hastily.

Abby’s phone remained silent. It seemed that her lifeline to the world had flat-lined. It was almost three hours since she had heard from Ricky.

She stared bleakly out of the window of the empty railway carriage, clutching the plastic bag into which she had scooped all the medicines she could find in her mother’s bathroom and bedroom. She told Doris that she was putting her mother in a rest home because she was worried about her ability to look after herself, and that she would phone her with her mother’s new address and phone number. Doris said she was sad to lose her neighbour, but that her mum was lucky to have such a lovely, caring daughter to look after her.

Some irony, Abby thought.

More and more of the sky was turning blue. Large clouds scudded across it as if they were on some urgent mission. It was becoming a fine, blustery autumn afternoon. The kind of weather in which she loved walking along the seafront, particularly the under-cliff walk at Black Rock, past the Marina and towards Rottingdean.

Her mother used to enjoy that walk too. Sometimes, they would do it as a family on a Sunday afternoon, her mother, her father and herself. She loved it when the tide was in, waves exploding on the groynes and sometimes smashing up against the sea wall itself, hurling spray over them.

And there was a time, somewhere back there in the mists of her childhood, that she remembered she had felt content. Was that before she had started going with her father to the big houses he did work in? Before she saw there were people who were different, who had lives that were different?

Was it then? Her personal tipping point?

In the distance to her left she could see the soft hills of the Downs as the train headed back towards Brighton. To where so many memories of her life lay. Where her friends still lived. Friends who didn’t know she was here. Whom she would have loved to see. More than ever she craved the company of her friends now. To pour her heart out to someone not involved in all this. Someone who could think clearly and tell her whether she was mad or not. But it was too late for that, she feared.

Friends were the one part of life that was not a game. But sometimes it was necessary to discard them, however hard that was.

Her eyes started watering. She had a sick feeling in the pit of her stomach. She’d eaten nothing all day except for the one digestive biscuit at Hugo Hegarty’s house, and she’d drunk a Coke on Gatwick Station platform a short while ago. She was too knotted up for anything more.