CHAPTER 21

the n2 “suite” in the tier one compound

jalalabad, afghanistan

0750 local time

The rhythmic scratch of a mechanical pencil on paper was an elixir for Whitney’s nerves. She often did her best thinking while sketching, when both hemispheres of her brain were fully engaged. Strands of rope looped and crossed, playing hide and seek on the page as they became impossibly interwoven. The design was of her own creation, meticulously imagined, then brought to three-
dimensional life as only someone who’d spent far too many hours contemplating and sketching knots could do. She pulled her hand away to look at the knot, then blew graphite dust off the page before continuing.

I have to find a new thread to chase . . . but how? Where?

The door opened and Petty Officer Yi walked in. Whitney looked up and acknowledged her with a close-lipped smile. Yi joined her at the table, parking her uber-petite body in the vacant chair beside her.

“What are you sketching?” she asked, leaning on her elbows for a look.

“A knot,” Whitney said, shading. Then, preempting the unspoken question, “Because I like knots.”

Yi smiled at this. “It’s quite an intricate and complex knot.”

“Intricate, yes. Complex, not so much.”

“Well, it looks complex.”

“To the untrained eye, but that’s an illusion. This knot is simple pattern repetition—seven interlocking trefoil knots.”

“What’s a trefoil knot?”

Whitney stopped sketching and rotated her forearm to show the other woman the triangular, beautifully inked three-lobed knot tattoo on the inside of her wrist.

“It kind of looks like a clover leaf.”

“That’s the origin of its name. Trefoil is the common name for Trifolium, which is the genus of three-leafed plants including clover . . . A trefoil knot is the simplest non-trivial knot.”

“What’s a non-trivial knot?”

“A knot that can’t be untied without cutting it.”

“Oh, I see, it’s one continuous strand,” Yi said, tracing her fingertip through the air while looking at the tattoo.

“Exactly. Trefoil knots are chiral.” Yi nodded, but Whitney could see from her woman’s expression that she wasn’t familiar with the word. “A figure has chirality when it’s not identical to its mirror image. For example, our hands are chiral,” Whitney explained holding up both hands—palms out, fingers up, and thumbs extended at right angles.

After a moment, it clicked for Yi. “Oh, I see, it’s like how you can’t wear a glove from your right hand comfortably on your left hand just by flipping it around. The thumb gets all wonky.”

“Precisely,” Whitney said, then moved her hands to align the back of her right hand to the palm of her left so the fingers closed in the same direction but the thumbs were on opposite sides. She then rotated her left hand so that the backs of both hands were touching. Now the thumbs were aligned, but the fingers and thumbs bent in opposite directions. “No combination of rotations or translations will achieve symmetry with chiral pairs,” she explained.

“I guess I basically understood that, but no one ever formally explained it, theoretically, I mean.”

“Whether a configuration is chiral or achiral is fundamental to knot theory.”

“Knot theory?” Yi repeated and screwed up her face. “Don’t tell me you’re some sort of math genius.”

“No, I’m definitely not,” Whitney said with a laugh. “One day I decided I wanted to get a Celtic knot tattoo, so I started trying to sketch one. No matter what I did, I couldn’t get it to look right, so I looked up Celtic knots online. One twist led to another—no pun intended—and I discovered there’s this entire field called knot theory. Mathematicians and puzzle makers have studied knots for thousands of years.”

“So basically, you’re a knot geek?”

“Yeah, pretty much.”

“Cool,” Yi said, returning her attention to the sketch. “Now that I see the pattern, I think it’s kind of beautiful.”

“For me, these knots are like a metaphor for working in the intelligence community. In order to properly draw a knot, you first have to understand how it’s woven, and if you understand that, then you can untangle it.”

“Is that how you feel right now?”

“Yeah.” Whitney sighed. “This case is just one giant knotted mess. I thought I was untangling it, but I don’t know . . . maybe I’ve been pulling on the wrong strand. What if we hit the wrong target? What if the Taliban doesn’t have a drone? What if they had nothing to do with the attack?”

“The ‘what if’ game is one I try to never play. You can beat yourself up all day asking those sorts of questions, and it won’t change anything,” Yi chided. Her expression suggested she knew what she was talking about, no doubt from years of experience working intel for Special Warfare.

“I know, but Chunk and the guys risked their lives because of our hunch. I can’t help thinking maybe I screwed up—trying to force a correlation between the convoy attack and the drone parts and Chinese missiles confiscated from that Pakistani freighter.”

“If we continue that line of reasoning, that would mean the battle damage assessment done by the guys at Oceana was wrong. Also, we’ve looked at the other scenarios and ruled out a mortar attack, RPG, and a surface-to-surface missile strike. Instead of second-guessing your initial conclusion, why don’t we focus on trying to find the drone? The question I keep asking myself is where did it go after the strike?” Yi said.

“Well, obviously poststrike they would want to fly it somewhere they could evade radar and try to land. The mountain valleys are a logical place to do that. Also, if the pilot flew it any direction but north, back toward the cave they were controlling it from, then he would eventually fly out of range and lose connectivity. The drone would cruise until it ran out of fuel, then crash, but we had people looking for drone wreckage, scouring the Afghan countryside, and we haven’t found anything.”

“What about in the mountains?”

“Bowman had eyes tasked to look for anything even remotely resembling a landing strip inside a hundred kilometer radius of the transmission site. The search turned up nothing.”

“What about outside a hundred kilometers?”

“Well, it’s kind of pointless to look outside a hundred kilometers,” Whitney said.

“Why?”

“Because a hundred kilometers is a reliable line of sight radius for a drone cruising at altitude. But try to land the drone and that range goes out the window. The moment the drone dipped below the mountain, they’d encounter interference. There’s no way they could have pulled off a landing in the Hindu Kush that was even a hundred kilometers out from the cave. And there’s no runway or wreckage in that valley below the Taliban stronghold we hit.”

“All right, then there’s your answer.”

“Huh? Explain, please.”

“They didn’t land it in the Hindu Kush,” the petty officer said with a victorious smile. “They landed it somewhere else.”

Whitney wasn’t sure whether to laugh or get angry with Yi, so she took a deep breath and said, “What do you mean somewhere else?”

“I don’t know. That’s what we’ve got to figure out.”

Whitney was about to fire back a snarky reply when her gaze fell on her knot sketch and an epiphany struck. “I know how they did it!”

“You do?”

She tapped her finger on her sketchbook at the junction between a pair of interlocking trefoil knots she’d drawn. “They used multiple line of sight transmitters to extend the operational range. Pretend each of these trefoil knots is the geographical area the drone can fly for a single LOS controller. Where two adjacent knots meet is a hand-off zone, if you will.”

“I’m with you. They didn’t have to land near the control station that executed the attack, they only had to fly the drone to the edge of another transmitter’s hundred-kilometer range and transfer control. After the handoff, the drone could be flown somewhere else to land.”

“Precisely,” Whitney said and shoved her notebook to the side to make room for a paper map of eastern Afghanistan and the Hindu Kush. Yi helped her smooth the map flat, then Whitney went to work, drawing with her mechanical pencil. “Okay, so this dot is the cave, which was also the location of the last recorded LOS signal in a drone-compatible frequency band. Now, if we draw a hundred-kilometer radius around the dot . . . we have this area of operation when the signal went dark.”

“Almost half of the circle is in Pakistan,” Yi said.

Whitney nodded and sketched three other circles that bisected the original circle: one northeast, one due east, and the third southeast. “Everything to the north and west inside Afghanistan is all Nuristan National Forest—rugged terrain, high altitude, and virtually uninhabitable. But east, across the border, the Khyber is packed with people and infrastructure. Look at all these cities: Peshawar, Mardan, Timergara, Batkhela, Mingora . . . not to mention the dozens and dozens of other Taliban-friendly villages scattered about. Those sneaky bastards,” she said, slamming her pencil down on the table triumphantly. “They flew it into Pakistan.”

“Okay, so what do we do now?” Yi said.

“We look for another source transmitting on the same frequency inside one of these three circles, close to the time the original signal went dark,” Whitney said, getting up from the table. “And we’re going to need some help to do it.”

“Are you going to Chunk with this?”

“Not without data,” Whitney said, retrieving the satellite phone from her pack and thinking about who in her existing network she could call who was senior enough to have inter-agency relationships she could leverage without running this theory up the Tier One command first.

“Then who are you calling?”

“My old boss at NCTC, Reed Lewis,” she said with an ironic grin. “Technically, he’s the reason I’m in this mess, so he can help me get out of it.”

“And if that logic doesn’t work?”

She shrugged. “Then I’ll beg . . . One must never underestimate the power of begging.”