She sat down in a chocolate-leather Barcelona chair. ‘So stupid of me,’ she said. ‘I should have known who you were, because cops and criminals are very much alike.’

Thorne sat down opposite her. ‘You think?’

‘We want to talk about David Mackenzie,’ Samarez said.

It seemed to Thorne, in the few seconds the girl took to say anything, as though she were deciding whether there was any point in claiming no knowledge at all of that name. The look on his face clearly made it an easy decision for her. Told her that she would simply be wasting time if she started lying.

‘OK, we can talk, but I don’t know anything, so . . .’

‘You don’t know anything?’ Samarez said. He nodded slowly and walked around the back of her chair. Sat down on the edge of a side table, so that Candela was between himself and Thorne. ‘You don’t know, for example, that David Mackenzie is not this man’s real name?’

She shook her head. ‘I don’t understand.’

‘You don’t know where all this money he spends on you comes from?’

This time, the shake of the head was more dramatic but far less convincing.

‘It doesn’t matter,’ Thorne said. ‘I don’t really care if you’re lying or not, because we don’t need you to tell us anything.’

There was relief on Candela’s face, then alarm. ‘So, what, then?’

What they would be asking of her was straightforward enough, but there would certainly be some risks. And the fact that she and Langford always got together at his place rather than hers was an added complication. It might have been about caution or control, or perhaps Langford simply preferred a big bedroom when he was on the job. But in the eight months he had been seeing Candela, he had not so much as set foot in her apartment, despite paying the rent on it.

‘We would like you to get something for us,’ Samarez said. ‘And don’t worry, we do not mean secret files or anything like that. You will not have to break into Mr Mackenzie’s safe.’ He smiled, leaned towards her. ‘Just a . . . cup, maybe?’ He shrugged, as though it were nothing. ‘Something like that; nothing too difficult for you. A glass or a spoon, something you have seen him touch.’

‘Something with a fingerprint,’ Thorne said.

‘These days we can get fingerprints off human skin,’ Samarez said. ‘But we do not want to put you to that much trouble.’

Candela spat a word at him in Spanish. Seeing Samarez suck in a fast breath, mock-wounded, Thorne did not need a dictionary to know that she had called him something very unpleasant.

‘Can you do it?’ Thorne asked.

She turned to him, pushed her hair back from her shoulders. ‘Why should I do this?’

‘Because we’ve asked you nicely?’

She stood up and told Thorne that he was not funny, that she was going to leave and that they could not stop her. But she was watching as Samarez produced a sheaf of photographs from his briefcase. He laid them out on the coffee table and she slowly sat down again.

‘These were taken three nights ago in the Shades nightclub in Puerto Banus.’ Samarez pointed at a picture of Candela talking to a man on the edge of the dance floor. ‘That is a very nice dress, Miss Bernal.’

Candela stared at the floor.

‘Did you have a good evening?’ He waited, but got no response. ‘Well, it is certainly one you will remember, because later you handed this man two hundred euros in exchange for two grams of cocaine. I know all this because this man is an undercover police officer.’

She muttered more words in Spanish.

‘We have more photographs as well as a voice recording of the transaction.’

‘Lucky for us that cops and criminals are so alike,’ Thorne said.

When Candela finally raised her head she tried to smile, but the panic was clear enough around her mouth and in the eyes that darted between Thorne and Samarez. Finally, she nodded slowly.

Samarez did the same. ‘That’s very good.’

‘You will need to protect me.’

‘Yes, of course,’ Samarez said.

He and Thorne were happy enough to offer at least a degree of the protection they had known Candela would demand. It had come as no surprise that she was afraid of Langford. And they were pleased to see no sign of loyalty to the man she was being asked to betray.

Earlier, Thorne had glanced at Samarez when the girl had talked about her trip to London. Samarez had given a small shake of the head. The Guardia Civil would have known if Langford had travelled to the UK. More significantly, Candela had said ‘a boyfriend’. It was apparent that Langford was not the only one with several partners on the go, that she took what she needed from their relationship just as much as he did.

If she had been in love with him, they might have had more of a problem.

‘When are you seeing David Mackenzie next?’ Samarez asked.

She leaned towards him and spoke low in Spanish. Samarez shook his head, having previously agreed with Thorne that all conversations must be in English, but Candela ignored him, talking fast and sounding increasingly desperate until he waved at her to shut up.

‘In English,’ he said, firmly. ‘Now, when are you seeing him next?’

She reached down to her bag and took out a pack of cigarettes. Smoking in an agency property was probably against the rules, but Thorne knew that holding on to her job was now the least of Candela Bernal’s worries.

‘Tonight,’ she said.

‘She offered me money,’ Samarez said.

‘After that,’ Thorne said. ‘She said something else after you shook your head.’

‘She offered me all sorts of things . . .’

Thorne found himself standing next to a middle-aged man with a Liverpool accent. ‘Mr and Mrs kind of thing, is it?’ he said.

The man laughed and began to describe the crowning of the feria’s King and Queen in such detail that, within a few minutes, Thorne was wishing he had not bothered to ask. The man, who turned out to be not only a resident of the village but one who prided himself on his extensive local knowledge, went on to deliver a potted history of the feria itself: the original sighting of the Virgin by two shepherd boys and the carving of her shrine into the rocks above the village by monks in 1548.

‘That’s where the name comes from,’ he said. ‘“Virgin of the Rock”. It’s quite funny, as it goes, because a lot of people get it wrong. They think “peña” means “pain”, but it’s actually “rock”. Or “cliff ”, if you want to be strictly accurate, like.’

‘Might as well get these things right,’ Thorne said.

The man pointed Thorne towards the site of the shrine, and Thorne seized his chance to escape, following a group of Japanese tourists up a gentle, winding slope until he reached the cave. It was predictably small and crowded. The entrance was blocked by those taking pictures, but Thorne could just see the candles throwing shadows on to the rock walls and across the statue of the Virgin, which would – so Thorne had been reliably informed by his know-it-all Scouse tour guide – be paraded through the village the following evening.

Thorne had no desire to go inside, so he walked across to a small wooden balustrade from which a few people were pointing video cameras. He squeezed in next to a young couple with two noisy kids and looked down into the valley.

‘Stop that, Luke!’

‘Don’t climb on there, Hannah, that’s really old . . .’

He thought about the past, both recent and long distant; what you honoured and what you tried to put behind you. He wondered if Alan Langford thought about his past quite as much as he did about his future. Thorne knew how carefully Langford planned his moves, how he always tried to anticipate what might lie ahead. But once those things had happened, once they had become part of his history, did they stay with him as much as they would with those whose lives he had ruined in the process?

At the side of him, the mother yanked one of her children down from the first rail of the balustrade, then swiped at the back of his leg.

How carefully Langford planned his moves . . .

What had Donna and Fraser said to him?

Alan never did anything by halves. He planned things out, thought them through . . .

He thinks a long way ahead, does Mr Mackenzie. Plays the long game . . .

Thorne moved away from the couple and their kids, took out his phone and called Holland. ‘Have a look through the original case notes and find out when Donna first met up with Monahan.’

‘What?’

‘The date,’ Thorne said.

Holland needed only half a minute. ‘In court, she said she couldn’t remember the exact date, but it was the last week of June.’

‘Right, and they killed whoever was in that Jag at the end of November.’

‘OK . . .’

‘Five months later.’

‘I’m not with you,’ Holland said. ‘We know that.’

‘What if Langford found out early on what Donna was up to? We don’t know when he got the tip-off, but if it was right after that meeting, he might have snatched whoever ended up in that car straight away. Someone he wanted to get rid of. I mean, he didn’t know Donna was going to keep losing her nerve and putting it off, did he?’

‘I suppose not.’

‘If Langford knew all along who was going to take his place in that car, he might have been holding on to the poor bastard for months, waiting for Donna to give the go-ahead, keeping him holed up somewhere. ’ The more Thorne thought it through and talked it out, the more it made sense. The more it seemed screamingly bloody obvious. ‘We’ve only been looking for people who were reported missing a couple of weeks either side of the killing,’ he said. ‘We’ve not been looking back far enough.’

He told Holland to get the mispers reports dating all the way back to early June ten years before. To start working through them with Kitson straight away.

‘Before you go,’ Holland said, ‘the DCI wants a quick word.’

As soon as Brigstocke came on the line, Thorne told him what he had just been discussing with Holland. Told him that the time frame made sense; that Langford was smart enough and cold enough. Brigstocke sounded pleased, but Thorne heard something in his voice, an enthusiasm that sounded forced.

‘What did you want, Russell?’

‘Adam Chambers,’ Brigstocke said.

Thorne tensed and began to walk back down the hill. ‘I hope you’re going to tell me he’s been hit by a bus.’

‘There’s some stupid campaign been started up to clear his name.’

‘What?’

‘The press have got hold of it and now some twat of an MP has jumped on board. It’s all over the news.’

Thorne called twice, and was told twice by Yvonne Kitson that he wasn’t helping.

The search parameters remained broadly the same. They were looking for missing Caucasian males of approximately six feet in height. The age of the victim was somewhat trickier. At the time of the post-mortem, there had been no reason to suspect that the body in the car was anyone other than the man identified by Donna Langford as her husband, and therefore no reason to examine bone fragments and tissue samples for an accurate assessment of the victim’s age. So, Phil Hendricks had re-examined the samples he’d taken during the PM ten years earlier. He established conclusively that the victim had not been drugged, but the damage caused by the fire meant determining a precise age was impossible.

‘Between twenty and fifty years old,’ Hendricks had told Holland. ‘But even that’s just a guess, and make sure you-know-who knows that.’ *

It was the second item.

Thorne was shocked to see that the MP Brigstocke had mentioned was a woman – young and earnest in a nicely cut business suit. She was standing outside Scotland Yard, the iconic sign revolving slowly behind her as she outlined the aims of the campaign.

‘Yes, Adam Chambers is innocent in the eyes of the law,’ she said. ‘But that is not enough. He has been traumatised by the experience of being falsely accused of such a terrible crime and is finding it desperately hard to rebuild his life. Mr Chambers is as much a victim as anybody. In fact, as far as anyone has been able to prove, he is the only victim in this entire shambolic investigation.’

Thorne was sitting on the edge of the bed, no more than a couple of feet from the small screen. ‘Bollocks,’ he said.

‘What do you want to see happen now?’ the interviewer asked.

The woman half turned towards the building behind her, skilfully alternating her tone between concern and outrage. ‘At the very least, Adam Chambers is owed an official apology, but I will be lobbying hard to see an independent inquiry launched.’

‘Do you have a message for the parents of Andrea Keane?’

Now the concern was even clearer in the studied nod and the lowering of the voice. ‘I have nothing but sympathy for the unfortunate parents of the missing girl. And I can assure you that Adam Chambers feels exactly the same way. But . . . on his behalf, on behalf of anyone who truly believes in justice, I’m demanding that those who sanctioned such a ridiculous and expensive prosecution be called to account.’

‘Can you tell us how Mr Chambers is coping?’

In the background, Thorne could see one of the Scotland Yard security officers watching, a machine-gun slung against his hip. He leaned forward to grab a beer from the mini-bar, slammed the door shut and heard the remaining bottles tumbling inside.

Imagined the officer taking aim and delivering a message of his own.