That was when the trail ran dry. There was no company in the UK with that name, and no one in the business community had ever heard such a name. Given the nature of what had happened, the police made extensive enquiries among the military, special forces and intelligence communities to establish whether they had heard of such an entity, but no one came forward.

  Cooper closed the file and looked up. The air in the vast room was still and cool. Dust motes danced in the air. Apart from the distant sound of traffic, he couldn’t hear anything at all. He stood up and walked down the long aisle towards the door, his footsteps ringing out. Before he reached the end, Margaret Kosminsky appeared in front of him.

  “Thank you,” he said, handing the file to her.

  She nodded curtly and turned away.

  “Why the secrecy?” he called out. “If we take the file at face value, it seems that a rogue outfit existed thirty years ago. They went too far, were almost caught and shut up shop as a result. There must be hundreds of files in this building that contain much more terrible things than that.”

  She turned back to Cooper with a fierce look in her eye.

  “Don’t turn out to be a disappointment, young man,” she said.

  The faintest gleam of a tear appeared at the edge of her eye, and she turned away.

  “You knew him,” said Cooper quietly. “Christopher Wilmshurst. This isn’t just another file to you, is it?”

  “Christopher was my cousin,” she said. “We grew up together. We were more like siblings than cousins.”

  She stepped closer and poked Cooper in the chest with the file.

  “They didn’t shut up shop, young man. That’s the problem. They just got better. The reason that we’re so careful,” she said, glancing around her and lowering her voice, “is that Hemlock is everywhere.”

  3

  “What did you make of Margaret Kosminsky, Eleven?” asked Control, the late afternoon sunlight pouring through the window blind and falling in pale stripes across his office floor.

  “Formidable,” said Cooper. “I’m surprised that you haven’t attempted to poach her over the years for a role here.”

  “I’ve certainly tried,” said Control with a rueful shake of the head. “It’s out of loyalty to the memory of her cousin that Margaret stays where she is at the National Archives.”

  “Cousin, sir?”

  “Christopher Wilmshurst. That file is the only thing I’m aware of that points to the existence of Hemlock, and she sees herself as its protector. She’s not going anywhere.”

  “Why does the file end where it does?” said Cooper. “Margaret told me that that’s not the end of it. ‘Hemlock is everywhere’ were her exact words. If she’s right, why isn’t the file filled with dozens of other examples of things that Hemlock has done over the years?”

  “I’ll give you two reasons. The first is that they know better than to leave evidence lying around. Have there been whispers over the years that some kind of private firm dealing in political influence and pressure is operating in the UK? Of course. Any astute observer of the political scene can discern from time to time the hidden hand of a powerful and malevolent actor. But in every single one of those cases, if you start to dig into the details, it’s very hard to lay your hands on anything that comes close to resembling proof. A witness changes their story or goes missing; items disappear from the police evidence room; CCTV cameras turn out to have been switched off for a crucial five-minute window. In one case I was involved in, we asked three separate medical examiners to conduct autopsies on the same cadaver because we were absolutely convinced that the deceased had been murdered, but all three examiners ruled that there were no suspicious circumstances. These people are good, Eleven. Very good.”

  “And the second reason?”

  “You tell me.”

  Cooper thought through what he’d learned. He’d had extensive experience over the years of private contractors, and in almost every single case the individual had learned their trade in government service. They might have previously been elite soldiers, senior police officers or even spooks, but it was almost unheard of for someone to enter that world as a total novice. There was no apprenticeship scheme when it came to wet work, blackmail and intelligence gathering. People learned to do these things for the state and then jumped ship and did the same thing in the private sector for a lot more money.

  “The two men who approached Wilmshurst,” said Cooper.

  “Yes?”

  “They knew what they were doing. They were former spies—former British spies. The reason they’ve been able to stay out of the spotlight since Christopher Wilmshurst’s death is that they have a lot of influence. They’re able to pay off the right detectives and twist the arms of newspaper editors into killing stories that mention the very existence of Hemlock. It’s not just that they don’t leave evidence. It’s that they have built a network across the whole of London that protects and shields them.”

  Control stood and crossed the room. He poured himself a stiff measure of single malt and held up the decanter to offer Cooper the same.

  “No, thank you, sir,” said Cooper.

  Control stood at the window and watched the sunlight playing on the Thames.

  “So much of this is conjecture, Eleven,” said Control. “But think about this: a firm that acquires and exploits political influence for others is also able to use that influence for its own purposes. If I’m right, Hemlock controls politicians on both sides of the aisle, as well as officials right across government. It’s not a surprise that they’ve been able to stay out of the limelight.”

  “If they’re the sort of company you describe, sir, it’s little wonder that Vanessa Clay got mixed up with them,” said Cooper. “She’d have the exact profile they look for: highly capable, experienced in covert operations, ruthless and amoral.”

  Cooper felt a rush of excitement and anticipation that he often experienced at the beginning of a job. In this case, though, he knew that he had his work cut out for him. In his fifteen years in the secret world, he’d never once heard the slightest whisper of Hemlock, or about the existence of an outfit that boasted such wide-ranging capabilities and influence. All that added up to one thing: this was a group of people who knew what they were doing.

  “Where do we start, sir?”

  “Vanessa Clay is the single best lead I’ve heard of in thirty years,” said Control. “Normally the only time you catch sight of Hemlock is once they’ve done something, but by that point they’ve cleared away the evidence and disposed of the witnesses. But if Vanessa was working on something for them that hasn’t yet happened, maybe we can find a way to catch them in the act.”

  Cooper stood.

  “I’ll get on it straightaway, sir,” he said.

  Something in his demeanour caught Control’s eye.

  “Everything all right, Eleven?” he asked.

  “It’s going to be hard to bring down an entity staffed with dozens of people who are as good as Vanessa Clay,” said Cooper.

  “Agreed,” said Control. “I suggest that it would be a mistake to try approaching this head-on for exactly that reason. Identifying what exactly Hemlock is—its personnel, structure, projects and capabilities—is only the first half of the challenge. The second half—how to destroy it—is where the going will get particularly thorny.”

  Control lifted his whisky glass in a silent salute to his operative.

  “Good luck,” he said, “and stay in close contact.”

  4

  When it came to Vanessa Clay, Cooper wasn’t making a standing start. Immediately upon his return from the biotech conference in Singapore where she’d betrayed him to the Chinese, Cooper had set about building a detailed and comprehensive picture of her lifestyle, associates, routines, interests and vulnerabilities. As a result, there was an enormous amount he already knew about her. He knew that she lived in a two-bedroomed flat in West Kensington, for example, and that she had a fondness for expensive mid-century modern furniture. He knew the three different running routes she favoured, all of which began at her front door, and her average times for each one of them. He knew what car she drove, where she parked it, the name of her personal trainer and the places she liked to shop. She was a solitary operator without many friends, but she did have a maternal aunt she was fond of who lived in Wimbledon.

  Cooper decided to take a leaf out of his opponents’ book. He keyed a number into his mobile.

  “Hello?” said an elderly voice.

  “Mrs Brooks?” he said. “My name is Brian Dexter. I’m a lawyer working for the firm of Hargreaves, William & Smythe. We’ve been hired by the former employers of your niece, Vanessa Clay, to tie up some loose ends and ensure that everything possible is being done to assist her relatives. I must start by saying how sorry we all were to hear the very sad news of her death.”

  “What did you say your name was?”

  “Brian Dexter. I was wondering if⁠—”

  “Is this about that box?”

  Cooper knew better than to let an opportunity like that pass by. “That’s part of it, yes.” He decided to push his luck. “I don’t want to waste any of your time, Mrs Brooks. Would it be all right if I came around now to collect it?”

  “Knock twice, young man,” she said. “Loudly. My hearing isn’t what it used to be.”

  Click.

  It took Cooper a little under twenty minutes to battle his way through the traffic and arrive at the small semi-detached bungalow several streets away from the world-famous tennis club. He didn’t know exactly what he hoped to find out from Vanessa’s aunt, but he knew how important it was at the start of an investigation to chase down every lead and push on every door, no matter how unimportant it appeared. There were all sorts of aggressive steps he could take to find out more about Vanessa Clay’s professional life, from breaking into the offices of the pharmaceutical firm where she worked to digging into the owner of the Highgate house Cooper had observed her visiting like clockwork every Tuesday evening. For now, though, an unsuspecting aunt in Wimbledon struck him as a good place to begin.

  It took a lot more than two knocks at the frosted-glass front door to get Mrs Brooks’s attention. In the end, Cooper had to go around to the back of the house and tap on the kitchen window.

  “I got so caught up going through the box that I didn’t hear you,” she said once she’d let him into the kitchen through the back door. “A right old trip down memory lane.”

  Cooper’s eye was drawn to the battered old shoebox on the kitchen table.

  “Would you like a cup of tea?” she asked.

  While she set about boiling the kettle and preparing a plate of digestive biscuits, Cooper wandered over the table and had a brief glance at the contents of the box. His heart had sunk slightly when she described it as ‘a trip down memory lane’. What he’d been hoping for were corporate secrets, coded correspondence or material that could be used to blackmail a political or commercial rival. That was the kind of thing he imagined might contain some clue to Vanessa Clay’s relationship with Hemlock. Instead, he could see a few dozen family photographs, a small collection of fridge magnets and a handful of Girl Guide badges.

  “I don’t want to take anything from here that you’d prefer to keep,” said Cooper.

  “She wanted you to have it.”

  Cooper had no doubt she was mistaken. There was no conceivable reason why Vanessa would have left a box of memories like that to anyone. He felt disappointed that his visit was turning out to be a wasted one but resolved to see if there was something he could salvage from picking Mrs Brooks’s brain.

  “When did you last see Vanessa?” he asked.

  “Two months ago. She was always so busy jetting off to one place or the other. That job of hers tied her up in knots, from what I could see. I just don’t understand why people do things that make them so unhappy. Are you happy, young man?”

  Cooper smiled.

  “Happy enough, Mrs Brooks. Some days are better than others.” He sat forward. “Can I ask, when did it first strike you that Vanessa was unhappy? I always thought she enjoyed her work.”

  “Oh, she did, she enjoyed it very much indeed. Until about three months ago. She never told me what had prompted the change, but she went from loving it to hating it. Something to do with a new client, that was as much as I could gather.”

  “Did she say anything about the client?”

  “She was secretive about everything, Vanessa was, but she was particularly secretive about this one. ‘It’s better you don’t know,’ she told me. I wager that she would have told me, given time, but then she had that terrible fall while hiking in Jordan.” A tear came to her eyes.

  Cooper felt a surge of guilt. She had been so warm and so welcoming that it bothered him to be withholding the fact that he was the person who had brought about her niece’s death. He hadn’t killed her; the fall had done that. But the reason Vanessa had been there in the Jordanian desert in the first place was to kill Cooper, and although he’d tried to save her, he knew that in the eyes of most people he was the one responsible for her death.

  “I’d better go,” he said, standing. “Thank you for the tea and biscuits, Mrs Brooks. I think I’ll leave the photographs with you, but I’m very grateful to you for showing them to me.”

  “You can’t leave without the box, young man.”

  “I really don’t think she meant it for me, Mrs Brooks,” said Cooper. “Besides, there are a lot of memories in here, and I think their rightful place is here with you, not in the offices of some law firm.”

  “She definitely meant them for you,” said Mrs Brooks, frowning. “There’s no doubt about that in my mind. No doubt whatsoever.”

  “How can you be so sure?” asked Cooper.

  She sighed with exasperation and pulled the box towards her, rummaging around in the bottom among the photographs.

  “Here,” she said triumphantly, handing a photograph to Cooper.

  He took it from her outstretched hand. It was a picture of a twenty-something Vanessa standing by the ferry pier in Portsmouth, her auburn hair blowing in the wind. Next to her stood an equally youthful Charlie Cooper.

  “Do you see? Vanessa showed me that picture just before she went to Jordan. ‘If anything ever happens to me, he’ll be the one who comes around,’ she said. ‘Make sure you’re nice to him. He’s got a good heart.’ Now, if that’s everything, I think it’s time for my afternoon nap. I’ll let you see yourself out.”

  5

  Cooper drove north from Wimbledon at a steady pace, sticking to the speed limits and making a few unnecessary detours to confirm that he hadn’t picked up a tail somewhere along the way. He was struggling to understand what had just happened. Before leaving for Jordan, Vanessa Clay had told her aunt that Cooper might come to her house and that if he did, she should give him a shoebox filled with assorted photos and old junk. Vanessa must have known at that stage that her trip to Jordan could have only one of two possible outcomes: either Cooper or Vanessa would die. If Vanessa died, she clearly wanted Cooper to… to what, exactly? To bring down Hemlock? Was that why she’d said the word as she fell to her death? And if that had been her posthumous wish, why hadn’t she left him a letter detailing exactly how he should go about that? What was he supposed to do with a shoebox filled with junk?

  Checking his rear-view mirror, Cooper clocked a black VW Golf that he’d seen earlier that morning. He turned left into a shopping centre without indicating and watched as the Golf continued straight without attempting to follow him. He loved multi-storey car parks for exactly this reason. Anyone following you had to stay close, which meant that it was a great way to draw hostile surveillance close enough to make a positive identification.

  After completing circuits of a few floors to confirm he was clean, Cooper pulled back out onto the busy A-road. He pressed a button on his mobile and waited as the call was patched through.

  “Hello?”

  “Nathan,” said Cooper. “It’s Charlie. Can you run a few checks for me? The address is 34 Manor Gardens in Highgate, north London.”

  He heard the sound of typing. There were up to a half-dozen Group Two technical experts whose expertise Cooper could draw upon if required, but he’d learned that even among that very elite group, Nathan Wiley stood head and shoulders above the rest.

  “There was an explosion at that address a few weeks ago,” said Nathan. “Is that the place?”

  “Yes,” said Cooper. “But I’m not interested in that. I want details of the owner. Name, age, former addresses, professional history. I can’t go into too much detail over an open line, but I need to confirm whether the person who lives there has any connection to a professional organisation engaged in blackmail, extortion and other forms of hard-edged coercive tactics.”

  “Give me thirty minutes. That’s usually long enough to at least work out if there’s something shady about a person or a business.”

  Cooper eased his BMW into a parking spot several streets away from the Highgate townhouse. The house at 34 Manor Gardens had been the one anomaly in Vanessa Clay’s weekly routine, which was precisely why Cooper had chosen it as the site for an attempted hit. The small explosive charge he’d concealed inside the hollowed-out frame of the garden gate had detonated as planned, but somehow the explosion had been more muted than he expected, throwing Vanessa backwards against the exterior wall of a neighbouring garage but leaving her alive. His assessment at the time had been that Vanessa was conducting an affair with the owner of the house, a former Conservative Party spin doctor called Timothy Powell.

  Cooper had watched as Powell’s wife left the house with their five children each Tuesday shortly before Vanessa arrived. He hadn’t tested his assessment; it didn’t really matter to him at the time why Vanessa went there every week. It was enough that she could be relied upon to be at the same place every week. That was all an assassin needed to do their work.