written by Cory Doctorow and narrated by Derek Perkins


But for the researchers, this was even more exciting. The fact that their algorithm had detected an information cascade where there was no actual command structure meant that it had found a latent structure. It was like they set out knowing what they were going to find, and then whatever they found, they twisted until it fit their expectations.

“Once we have the command structures all mapped out, everything becomes maths. You have a chart, neat circles and arrows pointing at each other, showing the information cascade. Who can argue with math? Numbers don’t lie. Having figured out their command structures from their chat rooms, we were able to map them over to their mobile communications, using the session identifiers the algorithm worked out.

“These twerps were half-smart, just enough to be properly stupid. They’d bought burner phones from newsagents with prepaid SIMs and they only used them to call each other. People who try that sort of thing, they just don’t understand how data-mining works. When I’ve got a visualization of all the calls in a country, they’re mostly clustered in the middle, all tangled up with one another. You might call your mum and your girlfriend regular, might call a taxi company or the office a few times a week, make the odd call to a takeaway. Just looking at the vis, it’s really obvious what sort of number any number is: there’s the ‘pizza nodes,’ connected to hundreds of other nodes, obviously takeaways or minicabs. There’s TKs—telephone kiosks, which is what we call payphones—they’ve got their own signature pattern: lots of overseas calls, calls to hotels, maybe a women’s shelter or A&E, the kinds of calls you make when you don’t have a mobile phone of your own.

“It makes detecting anomalies dead easy. If a group of people converge on a site, turn off their phones, wait an hour and then turn ’em on again, well, that shows up. You don’t have to even be looking for that pattern. Just graph call activity, that sort of thing jumps straight out at you. Might as well go to your secret meeting with a brass band and a banner marked UP TO NO GOOD.

“So think of the network graph now, all these nodes, most with a few lines going in and out, some pizza nodes with millions coming in and none going out, some TKs with loads going out and none coming in. And over here, off to the edge, where you couldn’t possibly miss it, all on its own, a fairy ring of six nodes, connected to each other and no one else. Practically a bullseye.

“You don’t need to be looking for that pattern to spot it, but the lads from the uni and their GCHQ minders, they knew all about that pattern. Soon as they saw one that the persistence algorithm mapped onto the same accounts we’d seen in the chat rooms, they started to look at its information cascades. Those mapped right onto the cascade analysis from the chat intercepts, same flows, perfect. Course they did—because the kid who told the best jokes was the most sociable of the lot, he was the one who called the others when they weren’t in the chat, desperate for a natter.”

I stopped him. “Thinking of your example of a group of phones that converge on a single location and all switch off together,” I said. “What about a group of friends who have a pact to turn off their phones whilst at dinner, to avoid distraction and interruption?”

He nodded. “Happens. It’s rare, but ’course, not as rare as your actual terrorists. Our policy is, hard drives are cheap, add ’em all to long-term retention, have a human being look at their comms later and see whether we caught some dolphins in the tuna-net.”

“I see.”

“We have their ‘command structure,’ we have their secret phone numbers, so the next step is to have a little listen, which isn’t very hard, as I’m sure you can appreciate, Mr. Holmes.”

“I make it a policy never to say anything over a telephone that I would regret seeing on the cover of the Times the next morning.”


“A good policy, though one that I think I might have a hard time keeping myself,” I said, thinking of the number of times my poor Mary and I had indulged ourselves in a little playful, romantic talk when no one could hear.

“Watson, if you find yourself tempted to have a breathy conversation with a ladyfriend over your mobile, I suggest you cool your ardor by contemplating the number of my brother’s young and impressionable associates who doubtlessly personally review every call you make. You’ve met my brother on a few occasions. Imagine what sort of man he would surround himself with.”

I shuddered. I had no interest in women at that time, and memory of Mary was so fresh and painful that I couldn’t conceive of a time when that interest would return. But I had cherished the memories of those silly, loving, personal calls, times when it had felt like we were truly ourselves, letting the pretense fall away and showing each other the truth behind our habitual masks. The thought that those calls had been recorded, that someone might have listened in on them—“just to check” and make sure that we weren’t up to no good . . . It cast those cherished memories in a new light. I wouldn’t ever be able to think of them in the same way again.

I was sure that Holmes had intuited my train of thought. He always could read me at a glance. He held my eye for a long moment and I sensed his sympathy. Somehow that made it worse.


My guest (Holmes went on) began to pace, though I don’t think he realized he was doing it, so far away in memory was he.

“The problem for the brain-boys was that these kids never said anything on their secret phones of any kind of interest. It was just a continuation of their online chat: talking trash, telling jokes, making fun of whoever wasn’t on the call. I wasn’t surprised, of course. I’d been reading their chat logs for months. They were just idiot kids. But for the spooks, this was just proof that they were doing their evil work using their apps. Damned if they do and if they didn’t: since it was all dirty jokes and messin’ on the voice chat, the bad stuff had to be in text.

“These boys were playing secret agent. They bought their burner phones following a recipe they found online and the next step in the recipe was to download custom ROMs that only used encrypted filesystems and encrypted messaging and wouldn’t talk to the Google Play store or any other app store whose apps weren’t secure from the ground up. That meant that all their mobile comms were a black box to the smart boys.”

“I imagine that’s where your checklist came in, then?”

He grimaced. “Yeah. That OS they were using was good, and it updated itself all the time, trying to keep itself up to date as new bugs were discovered. But we knew that the NSA’s Tailored Access Operations group had some exploits for it that we could implant through their mobile carrier, which was a BT Mobile reseller, which meant they were running on EE’s network, which meant we could go in through T-Mobile. The NSA’s well inside of Deutsche Telekom. By man-in-the-middling their traffic, we could push an update that was signed by a certificate in their root of trust, one that Symantec had made before the Certificate Transparency days, that let us impersonate one of the trusted app vendors. From there, we owned their phones: took their mics and cameras, took their keystrokes, took all their comms.”

“I suppose you discovered that they were actually plotting some heinous act of terror?”

My visitor startled, then began to pace again. “How did you know?”

“I know it because you told me. You came here, you handed me that extraordinary document. You would not have been here had the whole thing ended there. I can only infer that you exfiltrated data from their phones that caused our American cousins to take some rather rash action.”

He dropped down on my sofa and put his face in his hands. “Thing was, it was just larking. I could tell. I’d been there. One of these boys had cousins in Pakistan who’d send him all sorts of bad ideas, talk to him about his jihad. It was the sort of thing that they could natter about endlessly; the things they’d do, when they worked themselves up to it. I’d done the same, you understand, when I was that age—played at Jason Bourne, tried to figure out the perfect crime.

“They’d found their target, couple of US servicemen who’d had the bad sense to commute from the embassy to their places in the East End in uniform, passing through Liverpool Street Station every day. I suppose you know the station, Mr. Holmes, it’s practically a Call of Duty level, all those balconies and escalators and crisscrossing rail and tube lines. I can’t tell you how much time my friends and I spent planning assaults on places like that. That’s the thing, I recognized myself in them. I knew what they were about.

“We must have been terrors when we were boys. The things we planned. The bombs. The carnage. We’d spend hours—days—debating the very best shrapnel—what would rip in a way that would make wounds that you couldn’t suture closed. We’d try and top each other, like kids telling horror stories to each other around the fire. But I know for an iron-clad fact that my best friend Lawrence went faint at the sight of actual blood.

“The exploit we used to own their phones was American. It came from the NSA, from the Tailored Access Operations group. We had our own stuff, but the NSA were, you know, prolific. We have a toolbox; they’ve got a whole DIY store.

“Do you know what’s meant by third-party collection?”

“Of course.”


“Well, I don’t, Holmes.”

“Watson, you need to read your papers more closely. First- and second-party collection is data hoovered up by GCHQ and NSA and the Five Eyes, the so-called second parties. Third parties are all other collaborating nations that GCHQ and the NSA have partnerships with. Fourth-party collection is data that one security service takes by stealth from another security service. There’s fifth-party collection—one security service hacks another security service that’s hacked a third—and sixth-party collection and so forth and so on. Wheels within wheels.”

“That all seems somehow perverse,” I said.

“But it’s undeniably efficient. Why stalk your own prey when you can merely eat some other predator’s dinner out from under his nose, without him ever knowing it?”


My visitor spoke of third-party collection, and I saw immediately where this was going. “They saw what you saw, in the lads’ communications. They read what you read.”

“They did. Worse luck: they read what we wrote, what the analysts above my paygrade concluded about these idiot children, and then—”

Here he rattled that paper again.

“I see,” I said. “What, I wonder, do you suppose I might do for you at this juncture?”

“It’s life in prison if I go public, Mr. Holmes. These kids, their parents are in the long-term Xkeyscore retention, all their communications, and they’re frantic. I read their emails to their relatives and each other, and I can only think of how I’d feel if my son had gone missing without a trace. These parents, they’re thinking that their kids have been snatched by paedos and are getting the Daily Mail front-page treatment. The truth, if they knew it, might terrify them even more. Far as I can work out, the NSA sent them to a CIA black site, the kind of place you wouldn’t wish on your worst enemy. The kind of place you build for revenge, not for intelligence.

“It’s life in prison for me, or worse. But I can’t sit by and let this happen. I have this checklist and it told me that my job was to consider this very eventuality, and I did, and it came to pass anyway, and as far as I’m concerned, I have to do something now or I’m just as culpable as anyone. So I’ve come to you, Mr. Holmes, because before I go to prison for the rest of my life, before I deprive my own sons of their dad, forever, I want to know if there’s something I’m missing, some other way I can do the right thing here. Because I was brought up right, Mr. Holmes, and that means I don’t believe that my kids’ right to their father trumps those parents’ rights to their sons.”


“What an extraordinary fellow,” I said. Holmes was never one for the storyteller’s flourish, but he had an eidetic memory for dialog, and I knew he was giving it word for word—beat for beat and tone for tone. It was as if I was in the room with the tormented soul. The hair on my neck sprang up.


“‘Leave it with me,’ I told him, and showed him out. When I returned to my study, I found that I was curiously reluctant to do what I knew I must do. I found myself delaying. Smoking a pipe. Tidying my notebooks. Cleaning up my cross-references. Finally, I could delay no further and I went down to the station taxi stand and had a black cab take me to Mycroft.”


“Of course. When it comes to signals intelligence, my dear brother sits at the center of a global web, a point of contact between MI5, MI6, GCHQ, and the highest ministers and civil servants in Whitehall. Nothing happens but that he knows about it. Including, it seemed, my visitor.”


“Sherlock,” he said to me, once I had been ushered into his presence, “as unfortunate as this is, there’s really nothing to be done.”

The boom years since the 9/11 attacks have not been kind to my brother, I’m afraid. As his methodology has come into vogue and his power in the security services has grown, he has found himself at more unavoidable state dinners, more booze-ups at a military contractor’s expense, more high-level interagency junkets in exotic locales. Hawai’i seems a favorite with his set, and I’ve heard him complain more than once about the inevitable pig-roast and luau.

Always heavy, but now he has grown corpulent. Always grim, but now he has grown stern and impatient. Watson, my brother and I were never close, but I have always said that he was my superior in his ability to reason. The most disturbing change to come over my brother in the past fifteen years is in that keen reasoner’s faculty. By dint of circumstance and pressure, he has developed the kind of arrogant blindness he once loathed in others—a capacity for self-deception, or rather, self-justification, when it comes to excusing the sort of surveillance he oversees and the consequences of it.

“There is something obvious that can be done,” I told him. “Simply tell the Americans to let those boys go. Apologize. Investigate the circumstances that led to this regrettable error and see to it that it doesn’t happen again. If you care about excellence, about making the country secure, you should be just as concerned with learning from your failures as you are with building on your successes.”

“What makes you say that this is a failure?”

“Oh, that’s simple. These boys are a false positive. They lack both the wit and the savagery to be a threat to the nation. At most, they are a threat to themselves.”

“And what of it? Are these six fools worth jeopardizing the entire war on terror, the special relationship, the very practices at the heart of our signals intelligence operation?”

“Yes,” I said.

My brother colored, and I watched as that great mind of his went to work mastering his passions. “I’m afraid you don’t know what you’re talking about. It comes of being too close to the trees, too far from the forest. Human intelligence is fine as it goes, but when you conduct your investigations retail, you miss the patterns that we find in the wholesale end of things.”

“When one conducts one’s affairs at the retail level,” I told him, “one must attend to the individual, human stories and costs that vanish when considered from the remove of algorithmic analysis of great mountains of data.”

He sighed and made a show of being put upon by his brother. I expect that there are Whitehall mandarins who quake in their boots at such a sigh from such a personage. I, of course, stood my ground and ignored his theatrics.

“Come now,” I said. “There’s nothing to discuss, really. One way or another, the truth will out. That young man will not sit on his hands, whether or not I offer him a safer route to his disclosure. It’s not in his nature.”

“And it is not in mine to have my hand forced by some junior intelligence officer with a case of the collywobbles.” Mycroft’s voice was cold. “Sherlock, your client is hardly an innocent lamb. There are many things about his life that he would rather not have come out, and I assure you they would come out.” He made a show of checking his watch. “He’s already been told as much, and I’m certain that you’ll be hearing from him shortly to let you know that your services are no longer required.”

Now I confess it was my turn to wrestle with my passions. But I mastered them, and I fancy I did a better job of it than Mycroft had.

“And me?”

He laughed. “You will not betray a client’s confidence. Once he cries off, your work is done. Done it is. Sherlock, I have another appointment in a few moments. Is there anything further we need to discuss?”


I took my leave, and you have found me now in a fury and a conundrum, confronting my own future, and that of my brother, and of the way that I failed my client, who trusted me. For as you’ve seen, I kept my erstwhile client’s bit of paper, and the names of the boys he feared so much for, and have made inquiries with a lady of the press of whom I have a long and fruitful acquaintance. The press, Watson, is a most valuable institution, if you only know how to use it. I have been most careful, but as I have said on more than one occasion, my brother Mycroft has the finer mind of the two of us.”

He filled his pipe and struck a match. There was a sound at the door.

“I fancy that’s him now,” he said and puffed at his pipe. Someone who did not know him as well as I did may have missed the tremor in his hand as he shook the match out.

The door opened. Mycroft Holmes’s face was almost green in the bright light that lit it like the moon.

“You brought Watson into it,” he said, sighing.

“I’m afraid I did,” Holmes said. “He’s always been so diligent when it came to telling my story.”

“He is a veteran, and has sworn an oath,” Mycroft said, stepping inside, speaking with the air of a merchant weighing an unknown quantity in his scales.

“He is a friend,” Holmes said. “Sorry, James.”

“Quite all right,” I said, and looked at Mycroft. “What’s it to be, then?” I was—and am—proud of how steady my voice was, though my heart trembled.

“That is to be seen,” he said, and then the police came in behind him.

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