They’d agreed on Clifton Observatory in Bristol as the meeting point. This early in the morning it was eerily quiet. The school trips and tourists were yet to arrive, and sensible people who were not at work were all indoors. They were firmly on Avon and Somerset ground here, not more than seven miles from police HQ at Portishead, and they’d dispatched a team to Whitmarsh prison to fetch Hector Shaw in an escorted police van.

Anna had dressed warmly: puffer jacket, gloves and a woolly hat. Arctic plumes moving south across the county had plunged even the South-West into sub-zero temperatures. It had not snowed in Bristol but it was forecast as a significant risk. It wouldn’t last because yet more incoming Atlantic storms to the west were set to blow away the cold. But at this time of year, in the heart of winter, even that was a poisoned chalice.

Rainsford sat in his car, phone to his ear, but Anna, too restless to stay seated, stood outside with the rest of her MCRTF squad, namely DCs Justin Holder and Ryia Khosa. Holder, mid-twenties but looking ten years younger, defied the cold with the arrogance of the young in an unbuttoned padded jacket. He walked forward to meet the arriving transport and pointed to a space behind a Network Rail van parked with its bonnet pointing towards the city. Khosa, a good head shorter than Holder, her face barely visible under the fur-lined hood of the heavy coat she wore, spoke in a muffled voice through the scarf wrapped tightly around her mouth.

‘Bit different to the last time, ma’am.’

Anna nodded. She and Khosa had been in this situation before, the last time on a warm, muggy day in August in a park in Sussex. She’d known then that they’d have to indulge Shaw his ‘expeditions’ again but had not expected it to be in the middle of winter, like this. She felt he preferred the warmer months in order to make the most of getting out of prison, even for a day.

This demand, in the dead of winter, had a sense of urgency about it. Yet all he’d said, communicated to her through the governor of Whitmarsh, was that they needed to get access to the railway line near Leigh Woods. So here they were with two railway workers who’d brought keys to let them into the sealed-off access roads.

Holder came back to join the two female officers. ‘We’re following them in.’

‘Do we know where we’re going?’ Khosa asked.

‘He’s told the driver it’s a storage area somewhere down there, that’s all,’ Holder said.

‘Typical,’ Anna said. It was Shaw’s way. Keeping information to the bare minimum so they had no option other than to follow his lead.

Anna and Khosa hurried back to their Focus, one of two pool cars allocated to the unit, and followed the convoy. It took them across the suspension bridge, spanning the gorge with the dirty-brown river below, and down along the A369 towards Somerset until they got to Ham Green. There they turned right, back towards the river along narrow lanes only wide enough for one vehicle, until they got to a gate where the railway workers got out and used their keys. The Ford sagged on its suspension as the passenger side tyre found a pothole, causing Khosa to curse and apologise in the same breath. She pointed at the satnav on the dashboard and muttered, ‘None of these roads are on the map.’

She was right. The stoned tracks the Ford now navigated with such difficulty were Network Rail access roads used to gain entry to the railway for maintenance. Anna didn’t know this line – the old Bristol to Portishead line from the main station in Temple Meads out to the flat estuary land and the port. It was still used for freight, and the rumour was that they were going to make it a metro link by the end of the decade. But for now, it was a rarely used and desolate stretch through cuttings adjacent to the river, looping in towards Ham Green where there had once been a station.

They drove slowly parallel to the line, the narrow lane widening abruptly into a large, cleared area on which chippings had been laid. Their tyres crunched on the stones as Khosa pulled in and Anna stared out of the windscreen. The actual railway line ran only ten yards away. To her right stood stacks of sleepers, some concrete and others older and wooden. Next to them stood a ten-foot-high mound of grey track ballast chippings. All in all, the space must have been the size of half a football field. Where the stoned parking area ended, bramble and dead fern made a natural barrier bordering the woods beyond. It was a desolate spot.

The Network Rail van had parked in front of them. Holder got out and spoke to the driver. A minute later, the van drove off and Holder stuck his head down to talk through the passenger side window to Anna.

‘Not many people come down here, apparently.’

‘What is this place?’ Anna asked.

‘They call it a sleeper depot. Somewhere to keep spare ballast and sleepers for essential repairs on the line when needed.’

Anna looked at all the parked cars now with their doors closed. There were cadaver dogs and handlers, ground radar contractors, Rainsford, of course, and uniformed support.

All waiting for her.

She pulled on some gloves and got out of the car. Half a dozen other car doors opened as if on cue. From the police Transit, two uniformed officers emerged. Anna knew that at least one of those in the escort vehicle would be armed. She walked across to the van just as the rear doors opened and out stepped Shaw. His hands were cuffed in front of him and he wore a heavy coat over his lurid prison garb of chequered yellow and green. It was the first time she’d seem him in an ‘escape suit’. Someone in Whitmarsh, or even higher up in the Prison and Probation Service, must have decided that Shaw’s jaunts were a significant security risk. The boiler suits were designed to easily identify and prevent the escape of prisoners assessed as flight risks while being escorted outside the prison.

Watching Shaw blinking into the light, Anna was reminded of a bewildered jester transported from some ancient court. But there was nothing funny about Shaw as he stared at the surroundings, taking in the bleak landscape until his eyes landed on Anna. There they stopped and watched her approach. The prison had given him a hat to wear and it hid his shaved head, but his skin looked pale behind the thick glasses that distorted the contour of his face and made his eyes look smaller than they were.

‘Anna,’ he said in his slow Mancunian drawl. ‘Here we are again, eh?’

‘Hector.’ She used his name but didn’t offer a smile.

‘This is real witch’s tit weather,’ he said, shivering inside his coat.

‘Maybe we should get on with it, then.’

‘Good idea.’ Shaw started walking along the stoned area, looking up towards the denuded trees lining the railway and bordering the fields beyond. Anna, watching him carefully, walked with him, the uniformed officer within arm’s reach of Shaw and his gun-carrying colleague five yards behind.

‘What are you looking for?’ Anna asked.

‘I reckon it’s special. Needed a little bit of extra persuasion to tell me about this one did that shit-stain Krastev.’

Shaw hissed out the last two words of the sentence as if they were hawked up phlegm. Anna tried not to think about what it all implied and failed. Krastev, a vicious and sadistic criminal who had eluded capture in his native Bulgaria, Italy and Belgium by fleeing to the UK, had been embroiled in the Black Squid game and consequently Abbie Shaw’s death. Hunted down and captured by Shaw, Krastev had paid the price of that involvement with his life. But not before Shaw had managed to extract a great deal of information. Anna knew that whatever it was they were searching for on this freezing Monday morning would have Krastev’s bloody hands all over it. Such was the pattern. Shaw had already led them to more than one of Krastev’s buried victims, but it was his emphasis on the word ‘persuasion’ that made Anna squirm. As well as information about Krastev’s own murderous activities, Shaw had obtained links to other members of the Black Squid cell that Krastev had been a part of. Targeted by Shaw just as Krastev had been, the crime scene photos of their deaths showed that ‘persuasion’, in Shaw’s hands, was a chapter straight out of the medieval torturer’s handbook.

Shaw swivelled, scanning the horizon. ‘He said something about a fence.’

They passed a pile of wooden sleepers and then another. On the other side of the track a thin strip of dead fern and grass ended in more trees. Sometimes, when Anna took the train, she’d look at these strips of land adjacent to the embankments and cuttings and wonder how many thousands of acres of dead space it all added up to. Though nothing more than a fleeting thought before, now she was here, at ground level, it came back to her vividly.

Shaw kept walking until finally he stopped, quite abruptly, and said, ‘Here.’

Anna turned and followed Shaw’s pointing finger across the storage yard, between another stack of sleepers, and the pile of dumped grey track ballast. Through the trees she saw the geometric pattern of a fence, at least seventeen feet tall, black-coated metal with sturdy poles sitting on a concrete base.

Anna turned back and called to Holder. ‘Get the dogs searching this area.’

‘Yes, ma’am.’

Anna dropped her voice. ‘And find out what’s behind that fence.’

She turned back to Shaw. He smiled. ‘You’re looking fit, Anna.’

The nearest uniformed officer raised an eyebrow. Anna ignored it. She took no offence from Shaw’s words. She was fit and could hold her own in terms of endurance and physicality with anyone of her size and bigger. And she knew Shaw meant it in its truest sense, subtext-free.

‘Life must be treating you well,’ Shaw added.

‘As well as,’ she said.

‘Unlike me, then,’ Shaw said.

Anna frowned but Shaw didn’t elaborate. Instead he sucked in the cold air and exhaled loudly.

A few flakes of snow drifted through the air, wafted away on the brisk wind that seemed to cut right through Anna’s legs. The cadaver dogs were out of their van. She watched the handler give his instructions and saw the dogs start their work. Two springer spaniels with docked tails covered the ground like quicksilver.

Rainsford exited his car, his Crombie buttoned with the collar up around his ears. They’d agreed that he’d stay in the background so as not to antagonise Shaw. Much as she hated to admit it, Anna knew she was the link here and no one else. But Shaw looked across to where Rainsford stood, following Anna’s gaze.

‘Getting his hands dirty at last, eh, Anna?’ Shaw said.

‘You should go back to the van and wait,’ she replied before walking away.

She watched the cadaver dogs working for ten minutes until one of them, its stumpy tail twitching, turned abruptly, sat on its haunches next to a pile of the wooden sleepers and began to bark loudly. Holder signalled to the Forensics team, a couple of whom came forward with a small grey box on wheels attached to a long handle they could use to trundle the ground radar equipment over the earth. Within minutes they had a tent set up, largely to protect their laptop from the worsening weather. Anna went over and stood near the tent until Holder emerged.

‘It’s a positive, ma’am. Radar’s showing a definite disturbance here,’ Holder said.

Anna nodded. If this was another body, another innocent victim to find justice for, it was up to CSI to do their bit.

There remained the possibility, never far from Anna’s mind, that Shaw had been responsible for the killing and the burial in every case, and the narrative he’d invented to explain them all away was nothing more than manipulative lies. Though she had very little evidence to disprove this possibility, deep down in her core she did not believe he was lying to her. Yet today she’d already sensed something different about him. Less of the smug swagger of before.

Anna looked up at the grey sky and felt a snowflake brush her eyelashes. She turned and was walking back to where they were holding Shaw when Holder called to her. She looked back to see him standing next to another, taller stack of concrete sleepers. The cadaver dog handler was there next to the second dog, who’d parked herself on the ground, again barking loudly.

‘Ma’am, a word,’ Holder called out.

Anna crossed the space between them, rubbing her gloved hands together for a bit of warmth.

‘What’s wrong, Justin?’

‘It’s Zipper, ma’am, the second dog. Frank, here, thinks she’s found something, too. In a different spot. He wants the radar guys to take another look.’

Anna, her face stiff from the cold, stared at Frank. She’d not worked with him before. An ex-police dog handler, he now worked for a private firm specialising in buried remains. Frank shrugged an apology. ‘I’d put good money on it. Looks like it’s under this lot.’ He gestured towards the stacks of sleepers. There were four of them, each a pile of eight pallets with four sleepers on each palette.

‘We’ll need to move these,’ he said.

‘Justin, get back on to your Network Rail pals. I’ll speak to Rainsford.’ She waved at the superintendent, who immediately strode towards her.

‘There’s a problem, sir. Shaw only suggested there was one body, but the dogs have found something else in a second area,’ she said.

‘We need more manpower,’ Rainsford said. ‘I’ll get on to it, and we’ll need to discuss who’ll be senior investigating officer.’

Anna nodded. ‘These may simply be dead sheep, sir.’ The cold was beginning to seep into her bones.

‘He hasn’t shown us any dead sheep before, has he?’

Anna shook her head.

‘How is he? Shaw, I mean?’

‘Difficult to say.’

‘In what way?’

She shrugged and shivered. ‘Something’s off. Maybe it’s Shaw. He seems… different. Angry as always, that’s a given. But I can’t quite put my finger what else there is yet.’

Rainsford didn’t comment. Anna’s instincts were not to be scoffed at. Though the superintendent had never talked about it, they both knew it was part of her make-up and a useful tool. So far, those instincts had served her well in her ability to clear cases and deal with Shaw.

Rainsford glanced across at the Transit van. ‘Do you want me to tell him there’s more than one?’

Anna shook her head. ‘No point. He’ll only talk to me.’

‘OK.’ He glanced around at the desolate surroundings. ‘We’ll set this whole area up as a crime scene. I’ll talk to the crime scene manager and see what he thinks about moving those sleepers.’

Anna nodded. ‘Shaw’s reference point. The fence. Any idea what that is?’

Rainsford’s eyes narrowed. ‘It’s the northern perimeter fence of Ryegrove.’

‘But that’s near Leigh Woods. I had no idea it stretched this far.’ Anna turned to look back at the black fence.

‘Let’s hope it is just that. A reference point.’ Rainsford sighed. ‘You finish up here with Shaw and liaise with the CSM. First thing tomorrow we’ll have a briefing. We need to discuss strategy.’

Anna nodded. She wanted to ask him what he meant by hoping the fence was ‘just’ a reference point but he already had his phone to his ear as he walked back to his car, leaving Anna alone to digest this new morsel of information. It bothered her enough to make her want to scratch the itch. She walked back to the tent and stood behind it out of the worst of the wind and punched ‘Ryegrove Hospital’ into a search engine on her phone. Up came a page posted on a local history site.

When she finished and looked up, Shaw was waiting.

She walked over to the van, got into the front, turned and spoke through the grille. ‘We have one very likely spot,’ Anna said.

Shaw’s hands looked very cold in the cuffs. ‘I saw the second dog indicate. There’s something else here, isn’t there?’

‘We need to move the sleepers.’

‘Krastev said only one,’ Shaw said.

‘We’ll know for definite once Network Rail move their stuff.’

Shaw was shaking his head. ‘You need to stop them, Anna.’

‘Stop who?’

‘The bastards who are still out there doing this.’

Anna searched his face. ‘Doing what, Hector?’

‘Trapping mixed-up kids. Getting inside their heads, tormenting them with their sick games.’

Anna searched his face. Shaw turned away to look at the activity through a rear window. ‘Like that girl, Kimberley Williams. She had the Black Squid mark on her, just like Abbie.’

‘I don’t know all the details.’

Shaw turned back, his eyes blazing.

‘Honestly, I do not know,’ Anna said.

Shaw leaned forward. Though he was several safe feet away, the gesture made her want to move back. When he spoke, it was in a low whisper.

‘Then find out. I can’t stop these bastards, Anna. You have to.’

Anna glanced at the site and the crime scene tape already marking out areas where the dogs had indicated a find. ‘We’re going to need heavy machinery. It’s all going to take time.’

Shaw smiled and eased back into his seat. His lips looked dry and cracked. ‘You sending me back to my hole again, Anna?’

‘I have no intention of freezing to death out here.’

Shaw nodded. ‘You’ll let me know what you find.’

Anna didn’t answer as she started to get out of the van.

‘And when you do, I’ll help you even more.’

Beside her, the driver was staring, a look of distaste on his face. She hoped it was because of Shaw and not because he felt she was pandering to him. But she said nothing more as she exited the vehicle and walked away.

Anna sent Holder and Khosa back to HQ while she stayed, watching the forensic team do their dance, Shaw’s words gnawing at her like an irritating splinter. They’d been right to assume that the report of Kimberley Williams’ ‘suicide’ had got to him. It would have brought what had happened to his daughter bubbling to the surface all over again, and that was reason enough for him to be animated.

Yet Shaw’s impassioned plea for her to ‘stop these bastards’ implied that, in Shaw’s mind at least, the same perpetrators were involved. Anna considered that. Abbie’s and Kimberley’s deaths were sixteen years apart, but Shaw believed other bodies he’d shown her were Black Squid victims too. And this latest revelation threw up a list of unanswered questions that simmered in Anna’s head.

Was it possible that there were others? Was Kimberley Williams the latest in a longer line? Could there be an active killer out there with sights on yet another vulnerable young life?