“So each of those colorful little kinky threads on the screen is one possible backtrail?”

“Right the first time.”

Gladstone stared at countless squiggly lines. “Judging from this map, those virtual flaperons could have come from anywhere in a million square miles. This analysis didn’t work at all.”

“But at least it showed that some areas were more likely than others. They shifted their search after that.”

“But still didn’t find Flight 370.”

“No.”

“Like I said, their model was a failure. A total, balls-up failure.”

“But like I said—”

“And now you want us to replicate their failure?”

“Not the failure.” Lam rolled his eyes. “You see—”

“You want us to dump five million virtual feet into the sea off Turner Beach and backtrack them in time, to see where they started?”

This time, Lam waited until he was sure no more questions were forthcoming before he answered. “Yes, I do.”

“And why will that work for us when it didn’t for them?”

“We have more data on the gulf than they had about the Indian Ocean. And we only have to backtrack twenty-five or so days, not five months. But most important, I had a new idea about a way to analyze their data. I applied it to Flight 370—and when I did, all the floating debris models from the flight converged in one approximate area on the date of the crash. Instead of a thousand.”

Gladstone stared at the map. “So what’s your new idea?”

“I figured if I applied Feynman sum-over-histories diagrams to the possibilities, I might be able to eliminate the least likely pathways. Not every one of these squiggly drift patterns is equally probable: some are more likely than others. So you eliminate the unlikely ones—using Feynman diagrams.”

“What’s a Feynman diagram?”

“I’m tired now. How much will you pay me to explain?”

Gladstone frowned. Money and mathematics were all that Lam seemed to appreciate, even though he rarely had any of the former. “I’ll order extra cheese on our next pizza night. And onion. Okay?”

“Okay. It’s a mathematical and geometric way of diagramming the probability of particle interactions. Like in a particle collider? I just adapted the process to the ocean, treating it mathematically like a sea of interacting particles and forces. The math is terrifying and you need a supercomputer. But when it was done, this is what happened.”

He gestured at the screen. One by one, the colorful little threads disappeared from the map until nothing was left but the black arc of the airplane’s possible locations when it went down. Then, new threads began appearing on the map, all originating from Réunion Island. Some drifted one way, others jagged off in another—but they all converged, more or less, on a single spot in the ocean—on that black arc.

Gladstone shook her head. Was this another of Lam’s mathematical flights of fancy? “So that’s where Flight 370 is? There?” She pointed to where all the lines converged on the map.

“At the bottom of the ocean, of course.”

Gladstone stared. “Are you sure?”

“Well, obviously I have no proof. But I did run several billion Feynman diagram permutations through the university’s Q machine.” He sniffed again. “And I ran up a rather impressive CPU bill in the process.”

“How much?”

“Four grand.”

Mary, mother of Jesus. “And you didn’t clear it with me?”

He looked at her with an exaggeratedly wounded expression. “I didn’t realize it was going to go so high.”

“And you think you can do the same thing with floating feet?”

“Well, you’ve got tons of data from your floater experiments you’ve gathered over the past five years—much better than what they had for the Indian Ocean. I just need to figure out the floating characteristics of the actual feet to plug into the calculation.”

“What exactly do you need?”

“I’ll need two actual feet, along with a test tank of water with a wave and wind machine—they’ve got one at the oceanography lab at Eckerd.”

“And how much will all this cost, even assuming I can get ahold of some feet?”

He shrugged. “Another grand?”

“Jesus. And where are we going to get the money for that?”

“Why don’t you ask that FBI dude? He looked rich enough to me.”

17

ROGER SMITHBACK DROVE his Subaru along Cypress Lagoon Drive. For the last half hour, he’d been cruising around some neighborhoods south of Fort Myers—supposedly this was the more dangerous part of town, but he had seen mostly well-kept apartment buildings, schools, bodegas, small houses, even a decent-looking country club straddling Whiskey Creek.

This wasn’t what he’d expected at all.

Smithback had done his research. He knew that the tattoo he’d surreptitiously photographed was most likely a gang symbol of some kind. After he’d blown up and sharpened the image, it had become much clearer. It was definitely a cross, with lightning bolts coming out diagonally from the lower intersections of the crossbeam, and what looked like animal claws protruding from the top—although their tips were not visible, thanks to the tearing and nibbling of the torn skin. It was surrounded by two letters: a P on the left and an N on the right, done in the usual blackletter font of gang tattoos. Its color was the blue of prison tats, but that didn’t necessarily mean anything: it could just as well have been done at some Central or South American tattoo parlor. Because his research had indicated crosses done in this particular way—with a distinctive fleur-de-lis styling at the tips and an unusual method of decorative shading—were a trademark of gangs from south of the border.

But conventional research could tell him nothing further. And there were a shitload of gangs out there. He’d done his share of guessing about what the P and N could mean—Panama? Padre Nuestro?—but if he really wanted to learn more, he’d have to hit the pavement.

As a reporter, he’d heard back in the day about the troubles in Fort Myers—the Latin Kings, Surf 69, and the others: lots of drugs, lots of bad hombres killing other bad hombres. But there had been a concerted effort to clean this up, and the neighborhoods he’d previously heard mentioned, like Dunbar and Pine Manor, felt safe. Now, however, he found himself southwest of those, closer to the Caloosahatchee River. And as the blocks passed by, and he noticed more and more shuttered storefronts and graffiti tags sprayed on the sun-bleached walls, he grew confident he’d found a good place to start sniffing around.

He drove a little farther west, letting things get worse, then pulled over to the curb. He was on a block where old bungalows—the worse for wear—stood cheek by jowl with family businesses. About half the businesses were closed, windows painted white and front doors shuttered. Smashed or dented trash cans lay strewn about. Pickup trucks and a few old boat skeletons sat on cinder blocks in driveways or on front lawns, slowly moldering in the heat. A stray dog wandered by, tongue lolling. The air smelled of burnt rubber and garbage.

Smithback got out of his car and walked up to the first bungalow, which, not uncommonly in older and poorer communities, was half-hidden in overgrown tropical vegetation. The once-bright coat of paint had been reduced to faded and peeling strips. He pushed the doorbell—busted—then knocked. After a few minutes, he heard shuffling inside. Then the door opened halfway.