‘What about the other two?’ Holland asked.

If either of the two men whose names were below Dowd’s on the list possessed mobile phones, then they were pay-as-you-go, as there was no trace of any contracts. No trace of anything.

Simon Walsh had lived at seven addresses in the previous eighteen months, signing on at half a dozen different benefit offices before dropping out of the system. His only existing relative, an aunt, claimed not to have heard from him in ten years; and a friend who had last seen him six months previously said he thought Walsh might have become addicted to anti-depressants. Without being told why they were looking for him, the friend added, somewhat ironically, that he was always expecting to hear that Simon had been found dead somewhere.

According to Graham Fowler’s estranged wife, he had been sleeping rough somewhere in south-east London for at least two years, after an increasingly severe alcohol problem had cost him first his job, then his family. There was nobody of that name registered at any of the established day centres or night shelters.

‘Well, I can’t see us finding either of them through credit-card receipts,’ Thorne said. A few years before, he had spent a period undercover, living on the streets of the West End in an effort to find the man who was killing rough sleepers. He had met plenty like Simon Walsh and Graham Fowler, men who had slipped through the cracks by accident or design. ‘They both sound like people who don’t particularly want to be found.’

‘That might be what saves their lives,’ Holland said. ‘I mean, if we can’t find them…’

Thorne looked at the remaining name, which had been circled again and again in red felt-tip, as if in exasperation. ‘Not that finding them is the end of the problem.’

The one person on the list of potential victims that they had been able to track down was proving to be something of a handful. Despite repeated conversations and visits from family liaison officers, Debbie Mitchell was refusing to so much as consider the possibility of entering protective custody.

‘Well, she’s not all there, is she?’ Holland said.

‘She’s got problems.’

‘And there’s this business with her kid.’

Debbie Mitchell was the single mother of a child with severe learning difficulties. She had been arrested on three occasions for soliciting and on several more for possession of Class A drugs.

‘It’s weird, this drug thing,’ Holland said.

‘What thing?’

‘Catherine Burke did a few; now Debbie Mitchell. I should think there’s every chance with Walsh and Fowler, too.’

‘Not weird really,’ Thorne said. ‘Not when you think about what they’ve all got in common. You ask me, the weirdos are the ones who aren’t drug addicts or alcoholics.’

The office moved all around them, while they drank their coffees and stared at the board, as though the marker-pen lines and scribbles were symbols in some complex equation, the answer to which might suddenly present itself if they looked hard enough.

Three hours later, Thorne was standing in front of another board, looking at the list of lunchtime specials on the menu at the Royal Oak. Until recently, in what passed for the team’s local, ‘special’ might have applied to almost any food that was vaguely edible, but a new landlord had radically improved standards. An ex-copper himself, he knew that even police officers demanded more than shit and chips at lunchtime. It was still far from being a gastropub, but it had finally become something more than a last resort.

Thorne placed his order and took a Diet Coke and a bitter lemon back to a table by the fruit machine. He slid in next to Yvonne Kitson. They touched glasses and drank, their expressions making it clear that they would prefer a pint of strong lager and a cold white wine, respectively.

‘Later,’ Kitson said.

Thorne picked up a beer-mat and began methodically tearing it into tiny pieces. ‘This case is breaking new ground,’ he said. ‘It’s a “who-didn’t-do-it”.’

Kitson smiled, happy to play along. ‘Go on then, who didn’t do it?’

‘Well, since you ask… It wasn’t a primary school teacher in Doncaster, it wasn’t a photocopier repairman and keen amateur boxer from Wrexham, and it certainly wasn’t a seventy-eight-year-old ex-merchant seaman who’s retired with his wife to Portugal. It’s lovely weather there today, by the way, he told me so several times. He and his wife were planning to have lunch out by the pool.’

‘Three of your Anthony Garveys?’

‘My morning so far.’

‘Got to be done.’

‘Oh, I know,’ Thorne said. ‘And I’m loving every vitally important minute of it. I’ve been eliminating people from my enquiries like there’s no tomorrow. Putting lines through their names and ticking them off, just to be on the safe side, you know? Eliminating all day long. I am… the Eliminator!’

Kitson sipped her drink. ‘Fine, but I didn’t hear you coming up with any bright ideas this morning.’

Thorne finished ripping up the beer-mat and nudged the pieces into a nice, neat pile. He had nothing much to say and even if he had, seeing Russell Brigstocke turn from the bar and wave at them, he would probably have kept it to himself. Using basic mime techniques, he and Kitson were able to transmit their desire for more drinks, and once Brigstocke had bought them, he joined them at the table.

‘Have you already ordered?’

Two nods.

Brigstocke took a long drink of sparkling water and sat back. ‘I just lost fifteen minutes of my lunch-hour thanks to Debbie Dozy-Bollocks. ’

‘Still being difficult?’ Kitson asked.

‘You know an FLO named Adam Strang?’

Thorne nodded, remembering the Scotsman from the Macken crime scene.

‘Well, he spent most of this morning trying to talk sense into her, but she’s not having any of it. She’s just point-blank refusing to go anywhere. ’

‘How much has she been told?’

‘Not everything, obviously. Enough, though, or at least it should be.’

‘What are the other options?’ Kitson asked.

Brigstocke shook his head, like he was sick of thinking about it. ‘I’m reluctant to stick a car outside twenty-four hours a day just because she’s being stupid.’

‘Can we install a panic button?’

‘Not enough,’ Thorne said. ‘I don’t think Emily Walker or Greg Macken would have had time to push one.’

‘So, what else can we do?’ Brigstocke asked. ‘Arrest her?’

Kitson flicked a bright red fingernail against the edge of her glass. ‘That shouldn’t take too long, looking at her record.’

A waitress arrived with the food: lamb casserole for Thorne and fish pie for Kitson. Brigstocke stared down unenthusiastically at the bowl of pasta he was given, then pointed at Thorne’s plate.

‘I fancied that, but somebody had just ordered the last one.’

‘The quick and the dead,’ Thorne said.

They ate for a minute or so without talking, until Thorne said, ‘Why aren’t we involving the press with this?’

Brigstocke swallowed quickly. ‘I thought we went through this earlier on.’ He looked to Kitson for validation.

She nodded. ‘Keeping quiet about the serial thing.’

‘Right,’ Brigstocke said.

‘I’m not talking about that,’ Thorne said. ‘Why aren’t we getting photos of Dowd and the others in the papers, on the box, whatever? We can get something out of them for a change.’

This time Brigstocke took his time swallowing and answered quietly. ‘That’s… tricky.’ He looked around. Many of the team were eating at nearby tables.

Thorne pushed his plate aside and leaned closer to Brigstocke, just as one of the trainee detectives chose that moment to come over and spend five minutes pumping all his loose change into the fruit machine. There was nothing more said about the case until he had finished. Thorne made a comment about the machine being tight and watched the trainee walk away. Then turned back to Brigstocke.