Kill Decision

CHAPTER 22

Linda McKinney awoke to a warm breeze wafting over her face. As her eyes came into focus, she could see gauzy white curtains trailing away from a row of tall windows, undulating with the flowing air. The sun shone in, blinding white. She lay beneath a crisp linen sheet in a proper bed with a sturdy headboard made of rough-hewn pine. Clean down pillows cradled her head. Thick wooden beams traversed the ceiling above her. The walls were of mortared stone. This was an old place. A cross hung from the wall above the bed, and along the wall nearby were framed icons of saints and sepia-toned photos of brown-skinned, black-haired ancestors in starched collars and black dresses.

McKinney felt a sting in her hand and noticed an IV drip running from a needle taped in place in the top of her right hand. It led to an IV bag on a stand nearby. Her right leg felt tight near her pelvis, as though wrapped in bandages-and a biting pain came to her from somewhere deep in her upper thigh. She felt the tautness of stitches.

There was a gentle keek-keek sound.

McKinney looked to the footboard. A large raven regarded her and extended its wings. It then ruffled its throat and head feathers. Caw.

McKinney’s voice came out hoarsely. “Muninn.” She wasn’t sure why she knew the bird was female. Perhaps it was something in the bird’s manner. She just felt like she knew.

The raven caw ed loudly several times, then flew off between the gauzy curtains and out the window.

There were footsteps, and the heavy bedroom door opened to reveal an elderly woman with a deeply tanned, timeworn face. Her long gray hair was wrapped tightly, and she wore a dress of rough brown cloth with a richly embroidered white apron and collar.

McKinney nodded to her.

The old woman spoke soothingly. “Kehaca ti ictok.” She held up one hand.

McKinney tried to remember what Spanish she’d mastered on previous expeditions to South America. But then, she’d spent more time in the Amazon basin. Portuguese wasn’t going to help. Even so, this didn’t sound like Spanish. She cleared her throat and spoke in slow English. “Where is this place?”

The old woman smiled kindly, holding her arm and patting it gently. “Ni we-wen ci.” She turned to the heavy oak door bound by black iron hinges. “Lalenia! Lalenia!” The old woman’s powerful voice startled McKinney. Dogs barked from somewhere outside. McKinney tried to sit up a bit in bed.

More footsteps, and in a moment the heavy door opened again, revealing a much younger Latina in jeans and a white shirt. Her long black hair was tied back to reveal a beautiful almond-shaped face with mocha brown skin. She approached the bed and smiled, motioning to the old woman as she spoke in that same language. “Wala seh yanok Raton. ”

Then the younger woman turned to McKinney and spoke in Spanish-accented English. “How do you feel, Professor McKinney?”

McKinney looked around the room. “Weak. Where am I?”

“You’re in Tamaulipas near Kalitlen.” At McKinney’s blank stare she added, “Rural Mexico.”

“How long have I been unconscious?”

The young woman leaned over to say something quietly to the elderly woman, who nodded and left. The young woman then approached the side of the bed, producing a penlight from her shirt pocket. “You’ve been unconscious for several days. You lost a great deal of blood, and we’ve been rebuilding your platelet count.”

McKinney kept her eyes open as the woman checked her pupil dilation with the light. “I got shot.”

“Yes, I know. The bullet nicked your femoral artery.” The doctor lowered the penlight. “You were very lucky the damage wasn’t worse.”

McKinney remembered wrestling with a hellish toy-one whose brain she’d helped design. “Yes.” She felt suddenly very tired.

“Mooch is a talented surgeon. He was able to stop the bleeding, but it was close. And having O-positive blood probably saved your life.”

“Who are you?”

The woman placed a hand on her own chest. “I am Doctor Garza. You can call me Lalenia. We are in a very remote part of Mexico here. We don’t engage in formalities.”

“Your English is excellent.”

“I went to medical school in the States.”

“What was that other language?”

“That was Huastec, a Mayan dialect. My family has owned land here for generations. Rosario taught it to me when I was very young.”

“Medical school. Your parents must be proud.”

The young doctor became subdued. “My parents are no longer with me.” She took McKinney’s pulse, listening for several moments.

The door opened again, and this time a well-toned and muscular African-American man with a smooth bald head entered. He wore a Nike tank top shirt and cargo shorts. He was a striking male specimen in perfect physical shape. But what surprised McKinney was that he was missing both his legs beneath the knees. In their place were metal alloy prosthetic legs that he employed with such grace, she would never have known it if he weren’t wearing shorts. The prosthetic limbs ended in brightly colored running shoes that he apparently tied on just like anyone else.

Lalenia brightened considerably when he entered. “Raton, look who’s up.”

The muscular man smiled a tight, distorted smile as he walked to the end of McKinney’s bed. She could see now that the right side of his face was disfigured from a grievous wound whose scar tissue pulled at the side of his mouth. A horrendous scar ran along the side of his head to a stunted ear. He also appeared to be missing his right eye and had in place a false eye as black as onyx. He placed his hands on the footboard and she could see he was missing several fingers from his left hand as well. He had once been a handsome man, but he seemed not to notice.

He met her gaze and nodded. Then he spoke in a deep, mellow voice. “So, you’re the one who broke out of Odin’s isolation facility.” He started laughing midsentence. “That shows dash, Professor.”

McKinney stared at him. “Raton… Mouse. You’re Mouse.”

“You’ve heard of me.”

“A man named Ritter mentioned you. He made it sound as though you were-”

“Dead?” He nodded. “On paper, I guess I am.”

Lalenia walked over and kissed him on the cheek. “Not even close, baby.”

McKinney could see how much they cared for each other. Whatever scars he bore, Lalenia clearly did not see them.

Mouse focused on McKinney. “You ran into some difficulties back in the States.”

“Are we safe here?”

“Safe is relative. From them, perhaps, but only because you’re in the middle of a war zone. The cartels killed thirteen thousand people here last year. There’s more killing going on here than in Afghanistan.”

McKinney was at a loss for words. “Are you serious?”

“Most Americans have no idea how bad the fighting is down here. This will be JSOC’s next battlefield, Professor. Mark my words. Mexico’s constitution might prohibit U.S. boots on the ground, but there are workarounds.”

Odin walked in suddenly from the open doorway. He was wearing a faded gray T-shirt and jeans. He nodded to McKinney and let a slight grin escape. “I was worried about you for a while there.”

McKinney suddenly felt the reality of the situation. “I’m still worried about me. I can’t go home. And how long until they send machines here to kill us?”

He met her gaze and nodded grimly back. “Get some rest, Professor.”

E xhaustion came quickly to McKinney for quite some time, and she slept often. A week later she was sitting in the courtyard of a substantial-looking stone hacienda with a terra-cotta tile roof, enjoying the sunshine. The Christmas holiday and New Year’s had already come and gone, and she was morose with worry for her father. And for her brothers as well.

McKinney watched local children playing soccer in a dusty road nearby. She could see them through a wrought iron gate in a stone wall that enclosed one side of the courtyard. Their shouts brought back memories of Adwele playing with schoolmates in Tanzania. She wondered how he was coping with her sudden disappearance. Reaching out to him now would only put him in danger. She was helpless to do anything.

Instead, she stared into the distance. Beyond the houses were steep forested mountains, with clouds towering overhead. It was beautiful, but all she could think about was how to get back to her old life-and how impossible that now seemed.

Odin’s voice broke her reverie. “They said you were up and about.”

She looked up to see him standing in a nearby doorway.

“How are you feeling?”

McKinney shrugged. “Physically better. Psychologically, not so much.”

Odin came up clutching something wrapped in a burlap sack. He laid it on the table between them and sat in one of the rattan chairs next to her. Then he poured a cup of coffee from a steel pot nearby.

“How do you know about this place?”

“Years ago. We came down on an operation for the GWOT.” Seeing her confused expression he added, “The Global War on Terror. After 9/11 there were concerns about terrorists crossing the border, arms smuggling, that sort of thing. Turns out, the weapons were being smuggled the other way-from the U.S. to Mexico. We got caught up in a drug war.”

McKinney studied him. “You perplex me.”

“Why?”

“I just… why do you seek out war?”

He shrugged. “It’s what I’m good at. And there’s a bond you develop in war that’s hard to find in civilian life. People you can trust your life to.”

“But why get involved in Mexico’s drug war?”

“’Cause we were here. There’s a small number of vicious people destroying Mexican society to smuggle drugs into the U.S. Killing judges, reporters, men, women, children. We helped the locals who were trying to stop it. Those weren’t our orders, but we weren’t about to stand around and do nothing.”

“And Mouse?”

Odin nodded. “He met Lalenia. She refused to leave after the cartels killed her parents and her brothers and uncles. After they met, Mouse was always looking for an excuse to return here.”

“Is that how he…?” She gestured to her legs.

“IED. Central Asia. A few years back. Lalenia came up to Virginia to help him through physical therapy.” He pondered the memory. “Mouse was my commander, Professor. Team leader before me. He taught me everything I know. I needed his advice, and a safe place to regroup.”

“Apparently they think he’s dead.”

Odin nodded. “He’s a legend down here. El Raton — the Mouse. The cartels respect him. They found out the hard way that he’s an expert at insurgent warfare. He trained the locals to defend their land. To push the cartels out. Before that they were finding a dozen bodies in the street every morning. That’s over now.”

McKinney sat listening to the kids playing soccer for a while. The children laughing-untroubled by the momentous events of the world.

She gestured to the covered object in the center of the table. “What’s in the sack?”

“Something you should see. I didn’t want to alarm you until you were better.”

“I’ve been alarmed ever since I met you.”

“Okay, then…” He unfolded the burlap to reveal one of the black weaver-drone quadracopters that had attacked them in Colorado.

A slightly irrational fear gripped her. It was clearly dead-damaged and missing half its rotors. As a scientist, she was angered by irrational fears, so she tamped it down and leaned forward to look at the drone.

The core of it looked mostly intact, although none of the rotors at its four corners was still whole. The spikelike metal feet protruded menacingly, clearly sharpened like metal thorns.

“We managed to reconstruct this one by cannibalizing parts from the two that got into the plane cabin.” He picked up the lightweight device. “It wasn’t difficult. I get the feeling these were meant to be assembled by semiskilled workers. They’re modular, cheap. Mostly dual-use off-the-shelf parts. Circuit boards. Memory chips. Batteries. Optical sensors.”

She extended her hand, and he passed the dead drone to her. McKinney’s curiosity had already bested her anxiety, and she peered into its recesses, rotating it around. The broken propellers flopped around at the ends of wires. Her nose caught the peppery scent she remembered from the Colorado swarm. “There’s that smell again. Like cayenne pepper. I’d like to know the chemical composition.”

Odin nodded. “Mouse knows a few local chemists. Ex-cartel people. I’ll see if he can get it analyzed.”

She kept sniffing and traced it to nozzles next to a row of silvery capsules in the frame. They looked like the nitrous oxide cartridges used for whipped cream or the CO 2 propellant in paintball guns. “Four capsules. Like the chemical glands of a weaver. Mixing them in varying proportions to communicate different messages. That would match ant behavior. It’s how they lay down a pheromone matrix.”

“So they were leaving a trail.”

“It’s probably how they incite each other to attack. Each new arrival at a scene reinforces the attack message by spraying more pheromone. But that also means they’d need some way to read each other’s chemical pheromones.”

“Like an electronic nose.”

“Right.” McKinney ran her finger along one of four forward-facing wire antennas that were studded with tiny microchips.

Odin peered closely right next to her.

“Weaver ants-ants in general, actually-have dozens of sensilla on their antennas. They detect all sorts of things, chemical traces, heat, humidity. If these devices are running my weaver model, then they’d respond to numeric pheromonal input values. It’s virtual in my simulations, but here it could be a concentration measurement received from a hardware sensor. Weavers also transmit information to each other by touch, vibration.” She ran her fingers along each antenna, noting half a dozen small nodules.

“They transmit data to each other physically as well?”

McKinney nodded. “It allows them to move information through the swarm separate of the pheromones.”

“And we wouldn’t be able to jam that communication with radio countermeasures either.”

“I suppose that’s true of both the chemical and touch communication. But also, I was wondering how they found us-how they detected we were in the house, and where.”

“I was wondering about that too. These stupid little bots outperformed any system I’ve ever seen. We were wearing cool suits to hide our thermal signature and AD armor to conceal our human shape and faces. That fooled the sniper stations in the hills, but not these bastards. I was thinking maybe they reacted to noise or movement.”

McKinney shook her head. “If they’re using the weaver model I created, they’d focus on organic compound sensors. Ants have receptors in their antennas that help them identify food. Maybe-”

“You’re saying they smelled us?”

“Or tasted us.” She sighed. “I know it sounds silly, but that’s part of what weavers do when they swarm. They detect food sources by trace chemicals-in much the same way as they read each other’s pheromone messages.”

Odin seemed to be contemplating something. “It doesn’t sound silly at all, in fact.”

“What?”

“There’s a technology-well known in counterterrorism work, used by customs and Homeland Security. It’s called ‘C-Scout MAS.’ We used it while hunting for high-value insurgent targets.”

She examined one of the dead drone’s antennas. “I don’t know it.”

“It’s an electronic nose that sniffs the air to detect human presence. Apparently there are fifteen chemicals that indicate human presence by the breath we exhale-things like acetone, pentane, hexane, isoprene, benzene, heptane, alpha-Pinene. You get the idea. They appear in a specific ratio wherever people are breathing-the more concentrated it is, the closer people are or the more people there are.”

“You’re saying this technology is currently in use?”

“The detectors were on a microchip.”

She manipulated the articulated antennas on the dead drone. “Then maybe these drones find people in their vicinity by the gases we exhale-just like weavers would detect food. That would actually work well with my model. They could be coded to identify whatever they’re hunting by chemical signature-moving toward greater concentrations of the target scent and away from decreasing concentrations. That relatively simple algorithm is how my model works, and it manifests itself as complex hunting behavior when scaled up to a swarm of stigmergic agents.”

“We were breathing fast. Keyed up. We must have seemed like glowing neon signs to these things.”

McKinney was already looking more closely at the drone’s innards.

The drone had an aluminum tube frame, in the center of which was a wire box acting as ribs protecting the core. There was a stack of computer boards there, vision sensors all around, thin antennas-both leading and trailing-and wiring. Then along both sides were what looked to be steel cylinders-four in all.

Odin tapped them. “Zip guns. These were thirty-eights. They slide in on tracks, so it looks like they can have various weapon loads. The other one had. 410 shotgun shells.”

“They’re flying hand guns.”

“Dirt-cheap, highly inaccurate guns-but effective enough in close quarters.”

She examined what looked to be ports in the back. Charging sockets? There were also LED lights, all dead, but curious nonetheless. “If these run on my model, an appropriate number of workers would be ‘feeding’ the others. With weavers they pass along nectar-liquid food. Here, they probably pass along electricity, battery power. There seem to be electromechanical analogs for all the inputs and outputs of weaver swarm intelligence manifested in these things.”

She tossed it back onto the table in disgust. “But it looks like a toy. An evil toy designed by some sick, twisted-”

“Those ‘toys’ nearly killed all of us, and if we hadn’t fled, they would have. Lalenia pulled ten bullets out of our team, and that’s with body armor on.” He rewrapped the drone in its burlap shroud. “These things could be churned out of just about any contract factory in the industrialized world. Shipped anywhere by the thousands-just like toys.”

She looked up at him. “Oh, it’s worse than that. Those inputs and outputs-the stimuli and the response-they can take just about any morphology. These zip guns could just as easily be missiles. Those tiny rotors just as easily jet turbines.”

He narrowed his eyes at her.

“Ants are what’s called a ‘polymorphic’ species-they have various caste groups that can differ widely in size. For example, Pheidologeton diversus — the marauder ant-has supermajor warriors that are five hundred times the mass of one of their minor workers. And yet they are the same species and operate with the same brain-and belong to the same colony.”

“You’re saying these things could be easily scaled up using the same software brain.”

She gestured to the dead drone on the table. “I’m saying this might just have been a low-cost test version. A prototype. They could easily be made bigger.”

He contemplated this news. “Which means they will be. And I’ll need to take action before that happens.”

“Take action?” she asked. “I don’t know if you’ve noticed, but we’re all in hiding. The entire military-industrial complex wants us dead.”

“Not the entire military-industrial complex.” He looked calm and sipped his coffee. “Just part of it.”

She threw up her hands. “Oh. Well, then it’s the part that can monitor the FBI, fake your satellite communications, launch killer drones, and manipulate the media.”

He nodded. “Most of the military’s logistics have been privatized. Its computer systems. Its networks. Satellites. But there are still people behind it all, and most people who work in defense are just plain folks trying to protect their country. That’s our advantage. We just need to uncover who’s behind this. And I’m guessing it’s not a large group. That’s the appeal of these machines. They seem like something that would save American lives, but once built, they can be quietly controlled by a small number of unaccountable people. No coffins coming home from their secret wars.” He nodded to himself again. “But finding a small number of unaccountable people is doable.”

She stared at the table. “I don’t share your optimism. Weaver ants have survived almost unchanged for a hundred million years because they dominate every environment. If someone’s supersized them, and that design is out there-then what’s to stop this from spreading? You remember what Ritter said: Everyone wants this.”

“We were able to come to an international agreement about nuclear and biological weapons. So we should be able to come to some agreement about robotic weapons too.”

“Odin!”

They both turned to see a group of young boys at the gate. The lead one rolled a soccer ball on the tips of his fingers. He wore a bright yellow soccer shirt with the number twelve on it, but the other boys were in a mishmash of clothing.

The lead boy called out, “Mira, todavia tengo la pelota que me diste, quieres patear?”

The other boys urged Odin on.

He turned to McKinney. “If you’ll excuse me, I’m being challenged to a contest of skill.” He stood and walked toward the gate. “Bueno, Pele, vamos a ver como las mueves…” He hopped the wall, and the knot of boys took off after him down the street, laughing as mangy dogs barked and ran alongside them.

McKinney grinned slightly, watching through the gate, as Odin kicked the ball around with a growing knot of boys. He leaned down and said something that made them all laugh uproariously. It was a side of Odin she’d never seen. He seemed a natural ringleader, and it was apparent these boys knew Odin. They were at ease around him. She found it hard to square this side of him with the elite warrior.

She nearly jumped out of her skin when another voice spoke right next to her. “Mind if I join you?”

McKinney turned to see Mouse standing in the doorway of the hacienda. “My God, you scared me; I didn’t hear you come up.”

Mouse sat where Odin had just been. “That’s how I got my nickname.” He looked at Odin directing the boys into teams in the quiet, dusty road. “Ah, soccer. My game has suffered a bit.”

“I wouldn’t have guessed he was good with kids.”

Mouse nodded in the group’s direction. “They look up to him. He understands what they’re going through.”

“What’s that?”

“They’re orphans.”

McKinney now looked with concern at the young boys.

“Lalenia runs an orphanage for the children of the disappeared. It’s a lot of kids.”

McKinney looked into the street. “I knew David was an orphan, but I had no idea about these children.”

Mouse observed her closely for several moments. “He told you his real name?” He turned to watch Odin playing referee of an impromptu soccer match. “That’s interesting.”

“He didn’t exactly tell me. Another man said it in front of me. Some guy named Ritter-the same man who mentioned you. But David said his own name wasn’t important-that ‘Shaw’ was just the street they found him on.”

“He told you that much? And he brought you here. Are you two…?”

She held up her hands. “Oh… no! No, we’re just… colleagues.”

“Didn’t mean to embarrass you. It’s just that he doesn’t usually share information about himself. David doesn’t trust people easily.” Mouse studied her with his remaining good eye.

Nonetheless it felt like he was looking right through her. She squirmed.

“I worry that he’s missing a big part of life.”

“I imagine in his line of work trust doesn’t come easily.”

“You forget: I’m in the same line of work. And he came to us like this. As a kid, pretty much everyone who should have taken care of him, didn’t. He had difficulties. Learning disabilities. Turns out instead of being stupid, he was just very, very smart. No one checked. He grew up in juvie halls.”

McKinney watched Odin holding the ball up, the kids screaming with laughter. “Why are you telling me this?”

“Because that man is a brother to me. I love him like my own flesh and blood. David projects an image of invulnerability-like nothing can hurt him-but we both know that’s not true.”

McKinney nodded slowly and turned to see Odin bringing the soccer ball to one of the smaller boys.

Mouse took a deep breath and tapped the table. “The militia’s having a celebration tonight. To welcome back the old team. I hope you’ll come.”

“I’m not really up for a celebration.”

“There’s no better time to celebrate friendship than when things are at their worst.” With one last tap on the table he stood and silently departed.

I n the cool evening air the courtyard of the hacienda was filled with locals dressed in a wide array of inexpensive, but new, clothing-men in modern slacks with bright print shirts, cowboy hats, and boots; the women in cotton dresses and shawls. The courtyard was strung with white lights, and a stage had been set up against a wall near the garden, on which a large band of guitarists, violinists, vocalists-and even a harpist-were playing. The audience had cleared away tables and was dancing joyously.

McKinney limped along with a cane and stood next to a large tree, observing the festivities. It was a type of Mexican music she’d never heard before. No horns-almost like country or bluegrass. With a lively beat.

The aroma of a whole pig roasting over a fire pit came to her, along with that of vegetables and fruit being grilled. Tequila and beer flowed, along with wine. There were smiling faces and laughter all around her. She remembered this from war-torn areas of the world. No one treasured happy moments more than those going through dark times. Mouse was right about that. Community was what sustained people.

At the far end of the courtyard, among armed militiamen, Odin’s team was gathered in a circle, their arms around each other. Some of them looked seriously inebriated. McKinney could see the grief in their expressions. Smokey in particular wept as Odin rubbed his crew-cut head, comforting him. Foxy raised a beer bottle, and they all poured it onto the ground before them. It appeared to be a memorial rite for their fallen comrade.

Doctor Garza put her arm around McKinney. “How are you feeling, Professor?”

McKinney looked up. “Stiff, but I decided to take Mouse’s advice.”

“Good. You need to exercise the leg. No dancing, though.”

McKinney laughed. “Don’t worry.” She gestured to the band. “I’ve never heard a mariachi band like this.”

“That’s because it’s not mariachi. It’s a conjunto huasteco ensemble-probably a little different to your ears. Oh, look…” She pointed to Foxy, who had suddenly appeared onstage. He grabbed a small guitar as the band urged him to join them. “Foxy has a rare gift for the son huasteco. He must have some Mayan blood in him somewhere.” She grinned mischievously.

McKinney noticed that the group of mourning commandos had already broken up, and Foxy was taking the stage as the audience cheered and shouted encouragement.

“Foxy, toca una cancion!”

There was laughter and people clapping. McKinney couldn’t help but smile. On the edge of the gathering there were children as well, dancing and playing. Their laughter was infectious, as they shouted for Foxy to play.

Foxy started boldly strumming his borrowed Spanish guitar, and the crowd roared their approval as he fell in with the rest of the band. But soon he began to play around their music, weaving rhythms in and out as people cheered. He began to sing with a rich baritone voice. It was stirring, passionate music, whose lyrics McKinney couldn’t understand. But that wasn’t quite true. She could feel the bittersweet story in the emotion of music. It was just as Foxy had said back in Kansas City. Music transcended language.

McKinney had to admit the man had talent, all the more surprising given his headbanger proclivities. But she could see the truth in his belief that music connected people. All around them was joy, even amid sadness.

Mouse suddenly appeared out of the crowd and took Doctor Garza’s hand. “Senorita…”

Garza laughed and turned to McKinney as he led her to the dance floor. “Excuse me, Professor.”

McKinney smiled. “By all means.”

But just then she also felt a tap on her shoulder. She turned to see Odin. He stood silently for a moment as others moved around them.

McKinney motioned to her cane. “Doctor says I shouldn’t-”

“Follow me.” Instead of heading to the dance floor, he motioned for her to follow him as he headed toward the edge of the crowd. “I need you to see something.”

“Now?”

“Yes. Our guests are only here for tonight.” He was already moving ahead, and she limped after him with the cane. In a few moments it was apparent that he was leading her toward a barn not far from the main house. On the way, just beyond the lights and noise of the celebration, she was surprised to see armed militiamen standing guard in the darkness. They all nodded to Odin as he passed. It reminded her about another truth of war-there were no time-outs.

When they reached the barn, Odin brought her through a gap in the open doors into what appeared to be a workshop. Two men were gathered around a well-lit workbench there, one a younger Asian man, the other a distinguished-looking Mexican man in his fifties. Both were clearly dressed for the party but were now busy examining the damaged drone Odin’s team had reassembled from their encounter in Colorado.

The men both looked up as Odin and McKinney approached.

Odin nodded to them, gesturing to McKinney. “Gustavo, Tegu, this is the professor.”

They both nodded back and extended their hands. “Professor.”

Odin turned to McKinney. “Tegu used to manage communications for smugglers, and Gustavo was a senior chemist for the drug cartel that controlled this region.”

“You’re a chemist?”

Gustavo shrugged. “It was not my goal to work for the cartels, Professor. I was a chemical engineer, but then, sometimes we’re not given a choice. I have a wife and children.”

“I’m sorry. I didn’t mean to imply…”

Odin gestured to the workbench. “I sent chemical samples and asked Tegu to bring some equipment and have a look at our little friend-see if your theory about pheromones panned out.”

McKinney moved up to the workbench and could see Tegu using some sort of voltmeter to test connections on the black drone. “And what have you found?”

Gustavo answered instead, picking up one of the aluminum cylinders, but gesturing to the dead drone. “Fascinating design. This appears to be a chemical-dispensing, chemical-reading electromechanical machine. The pepper scent you smell is a diluted mixture of oleoresin capsicum, the active ingredient in pepper spray. This cylinder here contains o-chlorobenzalmalononitrile. It’s a lacrimator found in teargas. Both very common chemicals you might find present at any riot or civil disturbance.” Then Gustavo held up the remaining capsules. “But these two cylinders are the interesting ones. They contain what are known as chemical taggants, used by law enforcement agencies like your DEA and ATF to invisibly mark narcotics, or cash-or anything, really. We have run into these before.” He held up one metal cylinder for them all to see. “Perfluorocarbons-chemical structures that do not appear in nature. Odorless, colorless, and which dissipate at a predictable, measurable rate. You can reliably determine how much time has elapsed since they were applied.”

McKinney looked to Odin. “That’s just like the pheromone matrix of ants. The message dissipates over time. And is unique.”

Gustavo palmed the cylinders. “These are cyclic perfluorocarbon tracers that can be detected in concentrations as little as one in ten-to-the-fifteenth parts. This one is perfluoromethylhexane, and the other is perfluoro-1, 3-dimethylcyclohexane. These two chemicals, combined, could create a unique chemical signature-like a code.”

McKinney nodded to herself. “A colony-specific identifier. They could use it to identify their colony mates, and to organize colony activity.”

Tegu looked up from soldering several microchips to wire leads. Though Asian, he spoke English with no accent whatsoever. “Well, quite a few of the microchips on these antennas generate an electrical signal in the presence of a specific chemical signature.” He held up the evil-looking drone. “I managed to power it back up.” On McKinney’s alarmed look he smiled. “Don’t worry, I removed the gun barrels first. But it is a vicious little fucker…”

He held the drone up to McKinney’s face, and they immediately heard the firing pins on the gun rails clicking maniacally as it tried to kill her.

“Face-detection chip. Goes for a head shot if it can. I don’t know where you found this thing, but whoever designed it should seriously consider anger management counseling.”

Odin leaned in. “What about the chemical detector?”

“Oh, yes.” Tegu held up what looked like a modified voltmeter-the one he’d just been soldering. “Gustavo and I ran some tests and discovered which chips on these antennas are responsible for detecting the perfluorocarbons.” He ran his hand along the antenna that he’d grafted onto the voltmeter. “I removed the antenna and attached it onto this old voltmeter.” He pointed at the green LED numeric display. “The antenna detects the presence of these chemical taggants, and I’ve wired it so this display shows their concentration level.”

McKinney accepted the jury-rigged detector and held it up to the perfluorocarbon canisters. The LED readout immediately raced up into the hundreds. As she pulled it away from them, the readout started to count downward. “Meaning we can now follow their trail.”

Odin collected the cylinders from Gustavo. “Meaning we can hunt them. Hopefully back to their source.”