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.”
CHAPTER 23
Collateral Damage
Henry Clarke sat in a damask armchair next to his bed in an Egyptian cotton robe. A bottle of Dalmore fifty-year-old single malt was open on the table in front of him. A crystal glass of Scotch chilled by cold granite stones stood half-full in his hand.