They were both hungover and elated simultaneously: the sour and the sweet.

Junk TV became their focus that day, as neither one wanted to be the first to delve into a critical conversation.

“You have anything today?” Fisk asked her.

She studied the television, curled up sitting on his sofa now, a throw pillow beneath her bent left leg, chin on her bare knee. “Yeah,” she said, though her eyes didn’t sell it. “Actually there are some things I could do . . .”

“I wasn’t asking so you’d go,” he told her. “In fact, I was hoping maybe you could stay.”

She took her chin off her knee and looked at him. Profiling him for sincerity.

“Know this,” she said to him, “I swore to myself I’d never get involved with another cop. And I never have. Never.”

Fisk shrugged. “What makes you think we’re involved?”

Her eyes narrowed, taking the joke as intended. Fisk noticed the small gold detective’s shield replica, about the size of a nickel, dangling from a plain dog-tag chain around Gersten’s neck.

“Your father’s?” he asked.

She nodded, touching it with her forefinger. “His badge number. Four six three two. My mother gave it to me when I graduated from the academy. I take off everything else but this.”

Fisk tugged the pillow slowly out from beneath her bent leg. “Prove it,” he said.

“Miss me?” he asked now, many months later, speaking on the secure line from Ramstein Air Base.

“Intolerably,” she sang, a mix of exaggeration and honesty. “Everything good?”

“You know the drill. FBI is running it. They still hate me but they need me. And Geeseman’s still two parts asshole, one part haircut.”

“He’s probably monitoring all comm, FYI,” she told him. Gersten still lived with her mother, but stayed most nights at Sutton Place, even when Fisk was gone. “Wish I was in on it. That is some hot shit, you lucky dog. OBL. I’m walking around picking up trash dropped by snotty NYU Muslim kids again tomorrow.”

Fisk smiled. “Muslim beards are the new hipster goatee. You fix the faucet?”

“Nope. Couldn’t get it. Dropped a note to the super.”

“Lazy,” he said, stifling a yawn.

“It’s not my sink,” she said, and he could tell she was smiling. “All right, I can hear the exhaustion in your voice, and that you want to get back to it. Find something big, will you, hero?”

“I’m trying.”

“When you get home, I’ll properly debrief you.”

“Ah,” he said, smiling. “Do me one little favor. Say that again in a German accent.”

Chapter 12

Fisk pulled on sanitary garb again and moved through the air lock, returning to the bunker and the forensic search. Pearl and Rosofsky had never left, a quad montage of pornographic movies on the screens in front of them. A dizzying exhibition of the twenty-first-century incarnation of the human reproductive imperative, flickering past them at four frames per second.

“Learning anything, boys?” Fisk asked, watching over Pearl’s shoulder.

Pearl said, “I got numb to this stuff years ago.”

“Do you think you’re about ready to try it with a real human woman?”

“Someday maybe,” joked Pearl, sitting back, arms crossed, his eyes never leaving the skin game before him.

“Patterns, anything?”

“Definitely some random movies in here. A pattern, I don’t know. It would take a psychologist to say with authority what the big Laden got off on, and what was sent his way with messages encrypted. But I’m happy to report that sniffing OBL’s underwear ain’t part of my job description.”

“Just sniffing hard drives.”

“Exactly.” Pearl pointed off to the right. “Hard copies are on Geeseman’s table. The big beard was definitely using steg for moving info.”

“Thought so,” said Fisk.

Steganography means “hidden writing.” An old example from tradecraft would be a message written in lemon juice in between the lines of an innocuous letter; the lemon juice would turn brown when the paper was heated. In the digital age, a computer deconstructs the binary code for an image, translating symbols into complex images. A message may be embedded in such a file by adjusting the color of, say, every one thousandth pixel to correspond to a particular letter in the alphabet, and then transmit it. The alteration of the image is so minuscule as to be invisible to the human eye. If the viewer did not know the message was there, finding it among countless images on a person’s computer was virtually impossible.

Four years after 9/11, a twenty-five-year-old named Devon Pearl, newly hired by the National Security Agency after being caught hacking into their system, read a terrorist training manual recovered from a Taliban safe house in Afghanistan. It contained a section entitled “Covert Communications and Hiding Secrets Inside Images.”

Pearl found that no one at NSA was an expert on digital steganography, and so he became one himself. By late 2006, he developed the first practical search engine for ferreting out digital images that contained code anomalies indicating the presence of embedded steganographic messages. Pearl’s sniffer program—he was now on version seven—could fingerwalk through roughly one thousand still images per minute. For video, depending on the level of complexity, it could process five minutes in one. The program spit out a list of corrupt files with even a single pixel out of place. He then ran another program to weed out normally corrupted files—bad transfers—from the systematically manipulated ones.

It was possible now to encode plain text or mini-programs within images or movies that could crash a hard drive. A potential case of domestic terrorism the year before had turned out to be a rogue church of fundamentalist Christians using steg in gay porn to spike the computers of those the church deemed “sinful.” Members of an Al-Qaeda cell captured earlier that year in Milan were found with the usual array of pornographic downloads on their phones and computers, but also dozens of screen grabs from eBay sites selling diaper bags, used cars, furniture, and Hummel figurines. All part of a complex file-sharing communication network of terrorists who were piggybacking on legitimate Internet sites.

Pearl’s voice followed Fisk over to Geeseman’s lab table. “There’s not much yet, but after we defog the image, some of it is in plain text. No hard intel yet. But it’s clear that they’ve been busy.”

Fisk picked up the thin packet of printouts. He flipped through images of New York—no surprise, more than 50 percent of the traffic analysis at NSA headquarters at Fort Meade was Big Apple. The city had become an international terrorist obsession. By comparison, every other potential target in the United States was small potatoes.

These images were postcard views, though. Commercial photographs. Not handheld surveillance.

Geeseman walked over, perhaps concerned that Fisk was going to move something out of place on his lab table. “Refreshed after your break?” asked Geeseman.

Fisk suppressed an eye roll. Geeseman was a closet cigarette smoker who could not last more than two hours at a time inside the bunker. He and Geeseman had a purely professional relationship. Fisk’s rule-breaking reputation in New York had surely preceded him. “I had a quick hot tub and a rubdown, and now I feel like a million bucks.”

“I see you found the first scans.”

“Looks like the wonder twins are making progress. What about the others?”

“Slow and steady. Bonner, Elliott, and Cadogan are up to their ears with fantastic samples, but not much right-away intel. They’re going to spend the rest of the day cataloging for stateside forensics. We’ve got a C-17 picking it all up tomorrow about this time. Going to Dover for distribution to the task force agencies. Most of it’ll end up with Meade and Langley.”

Fisk shook the New York scans. “And Intel Division.”