Cooper sat back and looked at the ceiling as he thought through the implications of what Nathan had discovered. It seemed astonishing to him that Hemlock’s security standards were this rigorous and thorough. If you picked an average spook from the ranks of MI5 or MI6, Cooper thought, someone like Nathan would be able to find evidence of their employment on their devices. It might be that their location data put them in the vicinity of Thames House or Vauxhall Cross on a daily basis, or it could simply be that they switched off their phones during the working day. But for the police officer to have left absolutely no evidence of Hemlock behind confirmed Control’s warning that the group was operating at a very high level indeed.

  “That’s all well and good,” said Cooper. “But at the end of the day it confirms what we already knew: that the officer who owns this phone is linked to an extremely sophisticated network. Right? Have I missed something? Or is there some advantage we gain by knowing this?”

  Now it was Nathan’s turn to shake his head in exasperation. It was a constant source of frustration to him when other people couldn’t keep up.

  “Think of it as a pipeline. If something can travel one way down that pipeline, there’s nothing to say that something can’t travel the other way too.”

  “You can send stuff back.”

  “Exactly. They think they’re looking around my computer, but at the same time I’m sending questions back down the pipeline. Questions like: where are you located? What infrastructure do you have access to? How does your network operate? Because there’s a chance, Charlie—a remote chance, I’ll be the first to admit it—that I can use this pipeline to extract data from their servers instead of them doing that to us.”

  “You could find out everything about them? Who they are, what they’ve done, how they’ve been able to operate under the radar for all this time. How good a chance do you have?”

  Nathan slid open a desk drawer and stubbed his cigarette in an overflowing ashtray. He winked at Cooper.

  “Watch this space.”

  15

  Cooper sat in the back of the crowded coffee shop near Picadilly Circus and opened the laptop he’d just bought with cash from a second-hand shop on Tottenham Court Road. Given what he was about to do, he’d taken the precaution of placing a piece of tape over the camera and sticking gum into the microphones to make sure that they couldn’t be turned against him. He powered up the machine, connected to the café’s Wi-Fi network and typed a URL into the search engine that took him to the website of the small publisher that had repeatedly tried to purchase Anthony Scarwell’s diaries.

  The design was clean, simple and professional. At first glance, it looked like the website of every other small publisher working with limited resources. The background image showed a vibrant and colourful bookcase stuffed with modern paperbacks alongside classic editions, and the text running across the page spoke of ‘an enduring love of books of all shapes and sizes’. The only unusual thing about it was how little information it contained. There were no images of other books they had published, and no mention of who exactly was behind the company. Anyone stumbling across it by accident would dismiss it as belonging to a company that had probably gone under at some point, leaving the website to languish in a dark and dingy corner of the internet.

  There was a contact page, however. The text along the top read: Please send us a message if you’ve read and loved one of our books!

  Cooper typed:

  I’ve acquired a set of diaries that I believe you’re interested in. They were written by someone who died recently and contain a lot of information about the political world of the last few decades. If you’re still interested in purchasing them, send your best and final offer to the following email address: booklover3998@protonmail.com.

  There was no telling how long it might take them to reply. Cooper sipped his coffee, sat back and opened the first diary. He felt a small twinge of guilt at the fact he’d taken the diaries away from the author’s niece, but he’d grown a thick skin over the years and was able to rationalise what he’d done. It was always possible that he’d be able to return them once this was over.

  He turned the pages. The first volume covered the years 1995 to 2002. Tiny, spidery handwriting filled every inch of every page, and it didn’t take Cooper long to spot the first name that he recognised, that of a former BBC journalist who had since gone on to edit several national newspapers and take up a place in the House of Lords. The gossip about him didn’t amount to much more than rumours of a drinking problem and a prodigious temper, but as he turned the pages, Cooper came across dozens more names, many of which he didn’t recognise. Anthony Scarwell had clearly been a tremendous gossip with an insatiable appetite for stories that he could leverage for personal and political gain.

  The pace didn’t let up as Cooper glanced through the other volumes. There were accounts of extra-marital affairs, political backstabbing, friendships turned sour, drug use, financial fraud and even an account of an accidental death during a boat trip in 2020. Cooper wasn’t a regular follower of US celebrity gossip, but even he recognised the names involved. The most recent entry, completed just three days before Scarwell’s death, described a detailed allegation of electoral fraud in the US that Cooper had no doubt would bring down at least one high-profile politician if it saw the light of day. It was no wonder that an outfit like Hemlock would be keen to get their hands on this. Even if only half of what the diaries contained was true, there was enough of what the Russians called kompromat—compromising material—here to generate leverage and win influence right across the political landscape.

  Cooper turned to the laptop and refreshed the email account.

  A message.

  We remain interested in making a generous offer for the items described, it read. To verify that you are in possession of them, please take a picture of five random pages and send them to us.

  Cooper used the laptop camera to take photographs of three pages. He ran the pictures through a tool to strip the metadata from the pictures and attached them to his reply.

  You haven’t paid me any money yet, so three is all you’re getting.

  Send.

  He waited, listening with half an ear to a family of Australian tourists at the next table argue about which country made the best coffee.

  Another message.

  Tell us who you are and how you came by these diaries.

  They were clearly puzzled by the fact that their own operatives had failed to locate the diaries after Scarwell’s death, yet someone else had popped up willing to make a deal.

  A friend of the family, wrote Cooper. The author of the diaries told me that you were interested in buying them, so as soon as I heard of his death, I removed them from his house for safekeeping.

  Send.

  The reply landed within seconds.

  Understood. We are willing to pay 150K. We hope you will recognise that this is an extremely fair offer. To hand over the diaries and receive your payment, please go to St James Park this evening at ten pm and await further instructions.

  You must be alone.

  16

  As a rule, Cooper wasn’t a fan of disguises. Even if you were accustomed to wearing a wig or a prosthetic nose, which most people weren’t, you constantly ran the risk of some small detail looking unnatural or out of place. If you got into a fight, it could be even worse than that; it was very hard to stop the other person dislodging your disguise with a punch or a shove. The only times that disguises were useful, Cooper had found, was at a distance and in the dark. Otherwise, he avoided them at all costs.

  Tonight was definitely one of those situations that called for an exception to the rule. The darkness in St James’ Park was all-encompassing apart from the headlights of passing cars and the faint orange glow from one of the lampposts. Cooper shifted from foot to foot and looked around. He wore a sandy-coloured wig underneath his baseball cap and a pair of tortoiseshell glasses. The light disguise gave him some reassurance that Hemlock operatives in the vicinity would struggle to make a positive identification of the mysterious ‘friend of the family’ who had appeared out of nowhere with the diaries. Their priority would be a smooth handover, but they would no doubt be just as keen to know precisely who was taking their money. Although Cooper had flown underneath the radar for years, his image—along with that of every other British citizen—was stored with the passport office, the DVLA and a handful of other government databases. If Hemlock really had the capabilities that Control described, Cooper didn’t want to give them the opportunity to take his picture, work out who he really was and turn the tables on him.

  He checked his phone for a new email. The last one he’d received instructed him to stand by the drinking fountain by Birdcage Walk, but he was under no illusions that that was where the handover would take place. They would want to observe him to make sure that he was alone. He narrowed his eyes and peered into the darkness, shifting nervously. Somewhere nearby an owl hooted. He pretended to jump in alarm, wheeling around to see who was there.

  No harm in them underestimating him.

  His phone beeped with a new email.

  Walk straight towards the Blue Bridge, it read. Once across, turn right and proceed to the Guards Memorial. We will meet you there. Look for the woman with a red umbrella under her left arm.

  Cooper set off, squinting into the intense darkness to make out the shape of the bridge ahead of him. At the late hour there were only a few tourists in the park. A single jogger sped past him on one side, and a handful of teenagers drinking brightly coloured alcopops came the other way, laughing loudly at something one of them had said. He paused briefly at the top of the bridge, turning to glimpse a view that never failed to stir his heart of water glinting in the moonlight and, beyond it, the edge of Buckingham Palace.

  He crossed the bridge and turned right. He knew better than to expect there would be a woman with an umbrella of any colour waiting for him. It was the sort of thing that a nervous and inexperienced friend of Anthony Scarwell might expect to read in a message, but in reality, Hemlock would never provide a description of their operative in writing up front. They would want to preserve the element of surprise until the last possible moment. In fact, Cooper had no expectation he would get remotely close to the Guards Memorial. As a meeting place it was too close to the road, too close to the bright lights at the back of Downing Street and Admiralty House.

  Whatever it was they were about to do, they would want to do under the cover of darkness.

  Cooper didn’t hear them coming, but he did see the glint of a knife. One person sliced the strap of his leather shoulder bag and caught it before it could hit the ground. A second person pressed a small package into his hands, and a third person hit him across the back of his knees so that he fell to the path. It all took no more than three seconds.

  The cold muzzle of a weapon pressed against the back of his neck.

  “You have your money,” said a man’s voice. “Consider this transaction closed.”

  He heard the sound of footsteps running away into the darkness.

  17

  Cooper lay on the cold and damp path that ran through the centre of St James’ Park, his ears straining for any sound beyond the increasingly distant pat, pat, pat of fleeing footsteps. The package in his hands struck him as being the approximate size, weight and feel of one hundred and twenty-five thousand pounds in fifties and hundreds. Apart from a light bruise where the gun had been jabbed into the back of his head, he was unscathed. Whoever had wielded the knife knew what they were doing, and the blow to the back of his knees had been perfectly judged. It was possible that he was still being watched. Getting to his feet, Cooper stuffed the package into his jacket pocket and brushed the dirt from his trousers. He looked left and right in confusion and then set off at a run in the direction of Victoria station.

  There were two reasons for running. The first was that it fit with his cover of a hapless and naïve friend who had stumbled into something way above their head. The second was that he wanted to confirm that he wasn’t being followed. He knew the roads and alleyways in this area intimately and made a series of quick turns left and then right that would force anyone behind him into the open. He ran across Birdcage Walk and found himself turning onto Carteret Street, where he knew that at least half the streetlamps were permanently out of order. At the end was a private garden gate that was always left unlocked, and he stepped inside and pressed himself against the wall, his chest heaving, as he listened for the slightest indication that he’d company.

  He counted down from one hundred.

  He was clean.

  Stepping out of the garden, he walked a short distance and turned left into Petty France, keeping in the shadows. A dark grey transit van was parked at the end. As Cooper approached, the door slid open, and a grey cloud of smoke drifted out, followed by a single smouldering cigarette butt.

  Cooper jumped in and closed the door behind him.

  “Any sign they knew what we were up to?” asked Cooper.

  “None,” replied Nathan Wiley with a mischievous grin.

  “What have we got?” asked Cooper.

  “The first thing we’ve got is this,” said Nathan, reaching over to tap a screen. “I had a drone up over the park. The thermal imaging shows a total of four operatives deployed to the park, and if you fast-forward through the footage”—he pressed a button to speed up the frames—“you can see them all converging on you at precisely the same moment. From there they all leave the park in different directions. They’re very professional. No hesitation in their movements, and no radio communications between them to check on each other’s movements. It’s almost like a ballet the way they moved into position, executed their plan and then left.”

  Cooper and Nathan had discussed at length the best way to deal with the handover of the diaries. Cooper’s concern had been that if he adopted a violent approach and overpowered whoever came to collect them, it might leave him in a position in which he’d control over one or two individuals but no way of tracking back from them to the organisation that pulled their strings. That was the lesson both he and Nathan had taken away from Cooper’s encounter with the two police officers. Even if you got your hands on a Hemlock emissary, there was no guarantee that you could find out anything about Hemlock itself. In this case, that left them with only one possible course of action: follow the diaries themselves.

  “Any idea who they are?” asked Cooper.

  “I’m working on it. The drone footage shows where they left the park and entered the streets. I’ve got a programme downloading CCTV footage from the council cameras. There’ll be some clear shots among them. One thing I can tell you now is that this man was one of them.”

  He pressed a button.

  A black-and-white image of Pip Walker filled the screen.

  The MI5 head of internal affairs who had told Cooper that Hemlock was a myth.

  Cooper was almost lost for words.

  “Christ,” he said finally. “That explains why they set the two police officers on me. I was racking my brains trying to work out how I slipped up in my conversation with Timothy Powell. But I didn’t slip up—Powell knew from the moment I set foot across his front step who I was and why I suspected him.”

  Nathan tapped at the keyboard, and the image was replaced by a map. Cooper pointed at a flashing red dot.

  “Is that the tracking device?”

  “Yes,” said Nathan. “I’ve actually attached several devices to the diaries to ensure that we don’t lose coverage. It looks like your friend Pip is the one who’s been tasked with the job of delivering the diaries.”

  “Several devices?” queried Cooper, suddenly concerned. “He’s a very experienced field agent. He’ll have seen every tracking device known to man in the course of his career.”

  “Not these ones. I’m not using tech available to your average officer. The reason he won’t find them is that they’re not visible to the naked eye.”

  Cooper couldn’t keep a look of scepticism from crossing his face.

  “Transient electronics,” said Nathan. “Developed for use in medical procedures. Surgeons can implant devices that slowly dissolve over time, meaning that there’s no need for a second operation to remove them. The circuits are made from either water-soluble or bioresorbable metals that dissolve or metabolize into small, benign molecules.”

  “How transient is transient?”

  Nathan fixed him with a serious look.

  “Twenty-four hours. That’s as long as you’ve got.”

  18

  In some ways, thought Cooper, Corfe Castle was the unlikeliest location for an organisation like Hemlock to hide. The house he and Nathan had tracked the diaries to overnight was situated in a hundred acres of private woodland just on the edge of the Dorset village, named after the ruined castle that sat atop the Purbeck Hills. Thousands of tourists flocked to the area every year in search of clotted-cream teas and idyllic views, never for one moment suspecting that an organisation like Hemlock was hidden just out of sight behind the tall brick wall that encircled the property.

  As Cooper had expected, the journey that the diaries took on their way down to Dorset proved to be a long and circuitous one. Pip Walker was an experienced enough operative to know that the fact he couldn’t see a tracking device concealed in the diaries didn’t necessarily mean that one wasn’t present. From St James’ Park, Walker had travelled by car to a house in south London. The diaries stayed there for just over an hour, during which time, Cooper suspected, they were subjected to their first thorough examination. From there they were taken to a second property just outside Basingstoke. It was at this point that Cooper and Nathan Wiley began to fear that their plan would run into sand.

  It was only later that they were able to piece together what had most likely taken place in the Basingstoke property. It was evident to anyone who thought carefully about it that the diaries’ value lay not in the pages, the binding and the ink but in the information that they contained. The diaries themselves were of no value. It was the secrets they contained that Hemlock valued. Because of this, an obvious security precaution at this stage, before the diaries were delivered to their final destination, would be to photograph the pages and then destroy the diaries, rendering any tracking devices concealed inside them useless.