Daniel Suarez - Kill Decision

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.”