It was quiet when Anna got back to the office. Trisha only had eyes for her computer screen, busy with the nuts and bolts of the investigation. Dawes remained out and about. Anna took the opportunity to peruse Abbie Shaw’s file once more. She’d read through this many times over the last few months, trying to familiarise herself with the case in an attempt at understanding what made Shaw do the terrible things he had done.

There were several images of Abbie in the file, including four post-mortem which Anna had looked at once and then put back in the buff envelope that housed them knowing that she didn’t ever want to look at them again. The others were in a transparent folder. But the one that sat on top, the one she always brought to mind, was of Abbie just a few weeks before her death. The same one she’d put up on the board in the squad room.

She’d been a small girl – a factor, so the reports said, that might have contributed to the bullying she’d suffered at school. But Anna also saw an attractive face which would, with time, have blossomed. She wore glasses to correct her short-sightedness, like her father. For some reason this image was imprinted on Anna’s brain. It was how she thought of Abbie. The investigating team had pieced together Abbie’s last movements from witness reports and CCTV. Those movements and the subsequent enquiry were all in the file and Anna had read it so many times she almost knew it off by heart.

In December 2001, just a few weeks after her thirteenth birthday, Abbie caught the 192 bus from Manchester to Hazel Grove at 7.30 p.m. CCTV confirmed she got off at the stop near Crowcroft Park, crossed the A6 and entered Cayton Street, a dead end between a nursery and a breaker’s yard and vehicle service centre. At the end of Cayton Street, a refuse bin placed against the brick wall suggested Abbie had climbed up and over the iron railings, using the overhanging branches to hold on to. On the other side, beyond a few yards of overgrown wasteland, was the main Manchester to London railway line. At 8.05 p.m., Abbie stepped out from the darkness of the bushes into the path of the Stockport-bound train doing 75 mph. The driver did not see her, and her body, what was left of it, stayed at the edge of the tracks until a slower train picked her out two hours later.

Abbie’s mother had been almost impossible to arouse when the police went to call. She’d consumed the best part of a bottle of vodka and two of Chardonnay. She had not been aware Abbie had left earlier that evening and was convinced the police were mistaken and Abbie was asleep upstairs. Her screams, on finding her daughter was not in her bed, were heard two streets away. Abbie’s mother asked the police to contact Shaw and declined to do so herself. When asked why, she said she was scared of how he might react.

As it turned out she had excellent grounds for those fears.

Unlike his estranged wife, Shaw did not scream. The police report detailing the account said only that he became extremely quiet and still, listened carefully to what they had to say and then asked if they wanted him to identify the body. The SIO at the time counselled against it, but Shaw insisted. Anna often wondered if that one regrettable, weak moment on the part of the SIO might have thrown the switch in Shaw’s head that led to the maelstrom that followed.

She skimmed the reports of the digital seizures in the case. They’d found Abbie’s phone, damaged from the train impact. Calls and messaging did not reveal anything suggesting criminal behaviour, and her computer and ISP history had no clues other than a tendency for her Internet searches to dwell on MSN chat rooms and support groups for ‘acne sufferers’, ‘flirting with older men’ and ‘school blues’. Two of Abbie’s friends admitted they frequented Internet cafés in order to surf beyond the reach of prying parental eyes. Not one of them suggested that Abbie was suicidal, but she had admitted to feeling a need for ‘finding an answer to all the shit’. There’d been reports of name-calling in school, and one of her friends, a boy, had been hospitalised after being attacked for wearing the wrong kind of trainers.

On her computer screen, she’d left the Post-it note for her mother. It said, ‘Inky blackness, Mum. It’s the only way. Soz.’

Again, the police did not interpret this as anything other than a slanted hint at the dark depression that must have consumed Abbie. They looked and were critical of her dysfunctional family arrangement. An estranged father living on the other side of the city, an alcoholic mother, a lonely child with little or no guidance to hand. But someone guided her to a spot on an alleyway off the A6 with access to a high-speed train line. The report suggested she’d done her own research. The Black Squid, on the other hand, remained in the deep waters, out of sight and out of mind.

But not to Shaw. He wouldn’t accept that his daughter planned this act alone. When what was left of her was buried in the ground, he set about finding out the truth. His job as a network analyst at GCHQ gave him all the tools he needed, and posing as a troubled teen, he stalked the chat rooms and put together his own investigation. One that led to him tracking down some so-called ‘administrators’ of the Black Squid. By that time, months after his daughter’s death and consumed by silent rage, Shaw’s mind had slipped into psychopathy. He killed six people, including his wife, before police stopped him. And yet from Anna’s dealings with him, she knew he felt there was unfinished business. A consuming regret at not having reached all the people to blame for Abbie’s death. A fact Kimberley Williams’ recent death had now confirmed.

It was Holder’s beaming face around the edge of her door that interrupted these troubling thoughts.

‘OK, I’m guessing either you’ve won on a scratch card or your visit to the lab was worth it?’

Holder held up a piece of paper. ‘It’s not a scratch card, ma’am.’ He walked in with Khosa in tow and placed the paper on Anna’s desk. Blown up front and back images of the key card found on the female body, the faint outline of the image stamped upon it still unrecognisable, and next to it a passport-sized photograph of a woman with blonde hair and a zigzag parting.

‘This is the photo of Alison on the personnel file.’ Holder produced a smaller cut-out version of the image. ‘This is the same photo resized proportionately.’ He slid the cut-out image on to the image of the key card front. It matched the silhouette perfectly.

‘Bingo,’ Anna said.

Holder smiled, but it was the bemused grin of a child realising they were in the wrong classroom. ‘I don’t get it, ma’am. We’ve already had confirmation that the body is Alison Johnson’s. Why is this important?’

Anna explained, ‘Why would you have your key card in your back pocket, Justin?’

‘Because, you left it there?’

‘Why wouldn’t you have put it away?’

‘Because you were in a hurry?’

‘Exactly. Alison had finished work. She’d have a purse. She’d have put the card away unless she was in a hurry and slid it into her pocket without thinking.’

‘You think whatever happened was immediately after she left work that evening?’

‘Now I do.’ Anna looked out into the office as Dawes entered with four cups of tea. She stood to greet him.

‘When did you get back?’

‘Over an hour ago,’ Dawes explained. ‘Dropped the construction company employee list off with Trisha and went in search of Parky. You know Parky? Dave Parker? Been here longer than most. Still a sergeant like me but can’t bring himself to retire. Thought I’d pick his brains about those attacks on students around the time the Ryegrove fence was being worked on. He remembers it all right. Some break-ins, petty theft and a couple of girls scared by seeing someone loitering. Nothing came of it.’

‘What’s his take?’ Holder asked.

‘Very non-PC. He reckons there were a lot of outside workers on the Ryegrove project. Bound to be a couple of bad ’uns in amongst them – his words. They did some enquiries but there was no hard evidence, so it fizzled out. It was like once they’d made their presence felt, it scared the buggers off.’

‘And the construction company?’ Anna asked.

‘They weren’t that forthcoming when I rang so I went up there. Big offices on the industrial park up Swindon way. They were much more helpful with me cluttering up their reception than they were on the phone. Young lady by the name of Lauren printed off a list. Reminded me of that Beyoncé, she did.’

Anna saw Holder and Khosa hide a smile. Dawes was entertaining.

‘Anything come up?’

‘I’m still checking the names, ma’am. Lots of workers with similar surnames. It’s taking forever to run them through the PNC.’

Trisha got up from her desk and walked towards them. ‘I’ve just come across one name, ma’am. I haven’t run it yet, but it rang a bell with me because I’ve seen it before. I mean, I think it’s the same spelling, but you never know just from a name.’

‘Who, Trisha?’ Anna asked.

Trisha held up a piece of paper. ‘Mihai Petran.’

Anna looked at the name, highlighted in fluorescent yellow, and felt a little spurt of electricity firing off in her synapses. At the edge of her vision, both Holder’s and Khosa’s heads snapped up.

‘Please tell me this company, erm… Casperson, have images of their workers on file?’

‘I’ll get on to them.’ Trisha hurried away.

Dawes looked bemused. ‘Sounds like this bloke’s significant.’

‘Oh, he is. Very significant. If he’s the same Mihai Petran I think he is.’

‘So how does he fit in?’

Khosa answered with barely disguised distaste. ‘Petran is the identity stolen by Boyen Krastev, a Bulgarian lowlife on Europol’s red list for years. Wanted in Belgium, Italy and the Netherlands for abduction, sexual assault and drug-trafficking offences. According to the Border Agency, he’d never entered the UK.’

‘He nicked Petran’s ID?’ Dawes’ eyebrows shot up.

Anna nodded. ‘Krastev is also the man who told Shaw about Jamie Carson’s body before Shaw killed him. His contention was that he’d tracked Krastev down in the hunt for his daughter’s killer.’

Dawes sat down, a frown darkening his expression. ‘Really?’

Anna nodded. ‘Krastev was a facilitator, part of the Black Squid cell. Shaw’s victims were all members of that cell. And knowing what he did to them, if they knew anything at all they would have told Shaw.’

‘And you believe him?’ Dawes scepticism tilted the end of his question up half an octave.

‘Yes, strangely, I do. He’s not trying to hide anything he did. It’s Shaw who led us to Jamie Carson, remember.’

Dawes sipped his tea before saying, casually, ‘Course, we have considered the possibility that Shaw’s a manipulative speck of filth and that he could have buried both these bodies…’

Anna nodded. ‘But now we have Krastev in the picture. He was working at Ryegrove at the time Jamie Carson and Alison Johnson went missing. He was also, according to Shaw, involved in Daniel Litton’s apparent suicide. So I’m still inclined to believe Shaw’s version of events. Krastev is up to his neck in all of this. Unless anyone can come up with a better explanation?’

No one answered.

Anna looked at the silhouette of Alison on the key card. ‘Then it definitely looks like I’m going to have to ask Hector Shaw some questions a little sooner than I’d hoped.’