Systems security technician Phil Chartrukian had only intended to be inside Crypto a minute-just long enough to grab some paperwork he'd forgotten the day before. But it was not to be.

After making his way across the Crypto floor and stepping into the Sys-Sec lab, he immediately knew something was not right. The computer terminal that perpetually monitored TRANSLTR's internal workings was unmanned and the monitor was switched off.

Chartrukian called out, "Hello?"

There was no reply. The lab was spotless-as if no one had been there for hours.

Although Chartrukian was only twenty-three and relatively new to the Sys-Sec squad, he'd been trained well, and he knew the drill: There was always a Sys-Sec on duty in Crypto... especially on Saturdays when no cryptographers were around.

He immediately powered up the monitor and turned to the duty board on the wall. "Who's on watch?" he demanded aloud, scanning the list of names. According to the schedule, a young rookie named Seidenberg was supposed to have started a double shift at midnight the night before. Chartrukian glanced around the empty lab and frowned. "So where the hell is he?"

As he watched the monitor power up, Chartrukian wondered if Strathmore knew the Sys-Sec lab was unmanned. He had noticed on his way in that the curtains of Strathmore's workstation were closed, which meant the boss was in-not at all uncommon for a Saturday; Strathmore, despite requesting his cryptographers take Saturdays off, seemed to work 365 days a year.

There was one thing Chartrukian knew for certain-if Strathmore found out the Sys-Sec lab was unmanned, it would cost the absent rookie his job. Chartrukian eyed the phone, wondering if he should call the young techie and bail him out; there was an unspoken rule among Sys-Sec that they would watch each other's backs. In Crypto, Sys-Secs were second-class citizens, constantly at odds with the lords of the manor. It was no secret that the cryptographers ruled this multibillion-dollar roost; Sys-Secs were tolerated only because they kept the toys running smoothly.

Chartrukian made his decision. He grabbed the phone. But the receiver never reached his ear. He stopped short, his eyes transfixed on the monitor now coming into focus before him. As if in slow motion, he set down the phone and stared in open-mouthed wonder.

In eight months as a Sys-Sec, Phil Chartrukian had never seen TRANSLTR's Run-Monitor post anything other than a double zero in the hours field. Today was a first.

TIME ELAPSED: 15:17:21

"Fifteen hours and seventeen minutes?" he choked. "Impossible!"

He rebooted the screen, praying it hadn't refreshed properly. But when the monitor came back to life, it looked the same.

Chartrukian felt a chill. Crypto's Sys-Secs had only one responsibility: Keep TRANSLTR "clean"-virus free.

Chartrukian knew that a fifteen-hour run could only mean one thing-infection. An impure file had gotten inside TRANSLTR and was corrupting the programming. Instantly his training kicked in; it no longer mattered that the Sys-Sec lab had been unmanned or the monitors switched off. He focused on the matter at hand-TRANSLTR. He immediately called up a log of all the files that had entered TRANSLTR in the last forty-eight hours. He began scanning the list.

Did an infected file get through? he wondered. Could the security filters have missed something?

As a precaution, every file entering TRANSLTR had to pass through what was known as Gauntlet-a series of powerful circuit-level gateways, packet filters, and disinfectant programs that scanned inbound files for computer viruses and potentially dangerous subroutines. Files containing programming "unknown" to Gauntlet were immediately rejected. They had to be checked by hand. Occasionally Gauntlet rejected entirely harmless files on the basis that they contained programming the filters had never seen before. In that case, the Sys-Secs did a scrupulous manual inspection, and only then, on confirmation that the file was clean, did they bypass Gauntlet's filters and send the file into TRANSLTR.

Computer viruses were as varied as bacterial viruses. Like their physiological counterparts, computer viruses had one goal-to attach themselves to a host system and replicate. In this case, the host was TRANSLTR.

Chartrukian was amazed the NSA hadn't had problems with viruses before. Gauntlet was a potent sentry, but still, the NSA was a bottom feeder, sucking in massive amounts of digital information from systems all over the world. Snooping data was a lot like having indiscriminate sex-protection or no protection, sooner or later you caught something.

Chartrukian finished examining the file list before him. He was now more puzzled than before. Every file checked out. Gauntlet had seen nothing out of the ordinary, which meant the file in TRANSLTR was totally clean.

"So what the hell's taking so long?" he demanded of the empty room. Chartrukian felt himself break a sweat. He wondered if he should go disturb Strathmore with the news.

"A virus probe," Chartrukian said firmly, trying to calm himself down. "I should run a virus probe."

Chartrukian knew that a virus probe would be the first thing Strathmore would request anyway. Glancing out at the deserted Crypto floor, Chartrukian made his decision. He loaded the viral probe software and launched it. The run would take about fifteen minutes.

"Come back clean," he whispered. "Squeaky clean. Tell Daddy it's nothing."

But Chartrukian sensed it was not "nothing." Instinct told him something very unusual was going on inside the great decoding beast.