Susan's Volvo sedan rolled to a stop in the shadow of the ten-foot-high, barbed Cyclone fence. A young guard placed his hand on the roof.

"ID, please."

Susan obliged and settled in for the usual half-minute wait. The officer ran her card through a computerized scanner. Finally he looked up. "Thank you, Ms. Fletcher." He gave an imperceptible sign, and the gate swung open.

Half a mile ahead Susan repeated the entire procedure at an equally imposing electrified fence. Come on, guys... I've only been through here a million times.

As she approached the final checkpoint, a stocky sentry with two attack dogs and a machine gun glanced down at her license plate and waved her through. She followed Canine Road for another 250 yards and pulled into Employee Lot C. Unbelievable, she thought. Twenty-six thousand employees and a twelve-billion-dollar budget; you'd think they could make it through the weekend without me. Susan gunned the car into her reserved spot and killed the engine.

After crossing the landscaped terrace and entering the main building, she cleared two more internal checkpoints and finally arrived at the windowless tunnel that led to the new wing. A voice-scan booth blocked her entry.

NATIONAL SECURITY AGENCY (NSA)
CRYPTO FACILITY
AUTHORIZED PERSONNEL ONLY

The armed guard looked up. "Afternoon, Ms. Fletcher."

Susan smiled tiredly. "Hi, John."

"Didn't expect you today."

"Yeah, me neither." She leaned toward the parabolic microphone. "Susan Fletcher," she stated clearly. The computer instantly confirmed the frequency concentrations in her voice, and the gate clicked open. She stepped through.

The guard admired Susan as she began her walk down the cement causeway. He noticed that her strong hazel eyes seemed distant today, but her cheeks had a flushed freshness, and her shoulder-length, auburn hair looked newly blown dry. Trailing her was the faint scent of Johnson's Baby Powder. His eyes fell the length of her slender torso-to her white blouse with the bra barely visible beneath, to her knee-length khaki skirt, and finally to her legs... Susan Fletcher's legs.

Hard to imagine they support a 170 IQ, he mused to himself.

He stared after her a long time. Finally he shook his head as she disappeared in the distance.

As Susan reached the end of the tunnel, a circular, vaultlike door blocked her way. The enormous letters read: crypto.

Sighing, she placed her hand inside the recessed cipher box and entered her five-digit PIN. Seconds later the twelve-ton slab of steel began to revolve. She tried to focus, but her thoughts reeled back to him.

David Becker. The only man she'd ever loved. The youngest full professor at Georgetown University and a brilliant foreign-language specialist, he was practically a celebrity in the world of academia. Born with an eidetic memory and a love of languages, he'd mastered six Asian dialects as well as Spanish, French, and Italian. His university lectures on etymology and linguistics were standing-room only, and he invariably stayed late to answer a barrage of questions. He spoke with authority and enthusiasm, apparently oblivious to the adoring gazes of his star-struck coeds.

Becker was dark-a rugged, youthful thirty-five with sharp green eyes and a wit to match. His strong jaw and taut features reminded Susan of carved marble. Over six feet tall, Becker moved across a squash court faster than any of his colleagues could comprehend. After soundly beating his opponent, he would cool off by dousing his head in a drinking fountain and soaking his tuft of thick, black hair. Then, still dripping, he'd treat his opponent to a fruit shake and a bagel.

As with all young professors, David's university salary was modest. From time to time, when he needed to renew his squash club membership or restring his old Dunlop with gut, he earned extra money by doing translating work for government agencies in and around Washington. It was on one of those jobs that he'd met Susan.

It was a crisp morning during fall break when Becker returned from a morning jog to his three-room faculty apartment to find his answering machine blinking. He downed a quart of orange juice as he listened to the playback. The message was like many he received-a government agency requesting his translating services for a few hours later that morning. The only strange thing was that Becker had never heard of the organization.

"They're called the National Security Agency," Becker said, calling a few of his colleagues for background.

The reply was always the same. "You mean the National Security Council?"

Becker checked the message. "No. They said Agency. The NSA."

"Never heard of 'em."

Becker checked the GAO Directory, and it showed no listing either. Puzzled, Becker called one of his old squash buddies, an ex-political analyst turned research clerk at the Library of Congress. David was shocked by his friend's explanation.

Apparently, not only did the NSA exist, but it was considered one of the most influential government organizations in the world. It had been gathering global electronic intelligence data and protecting U.S. classified information for over half a century. Only 3 percent of Americans were even aware it existed.

"NSA," his buddy joked, "stands for 'No Such Agency.' "

With a mixture of apprehension and curiosity, Becker accepted the mysterious agency's offer. He drove the thirty-seven miles to their eighty-six-acre headquarters hidden discreetly in the wooded hills of Fort Meade, Maryland. After passing through endless security checks and being issued a six-hour, holographic guest pass, he was escorted to a plush research facility where he was told he would spend the afternoon providing "blind support" to the Cryptography Division-an elite group of mathematical brainiacs known as the code-breakers.

For the first hour, the cryptographers seemed unaware Becker was even there. They hovered around an enormous table and spoke a language Becker had never heard. They spoke of stream ciphers, self-decimated generators, knapsack variants, zero knowledge protocols, unicity points. Becker observed, lost. They scrawled symbols on graph paper, pored over computer printouts, and continuously referred to the jumble of text on the overhead projector.

JHdja3jKHDhmado/ertwtjlw+jgj328

5jhalsfnHKhhhfafOhhdfgaf/fj37we

ohi93450s9djfd2h/HHrtyFHLf89303

95jspjf2j0890Ihj98yhfi080ewrt03

jojr845h0roq+jt0eu4tqefqe//oujw

08UY0IH0934jtpwfiajer09qu4jr9gu

ivjP$duw4h95pe8rtugvjw3p4e/ikkc

mffuerhfgv0q394ikjrmg+unhvs9oer

rk/0956y7u0poikIOjp9f8760qwerqi

Eventually one of them explained what Becker had already surmised. The scrambled text was a code-a "cipher text"-groups of numbers and letters representing encrypted words. The cryptographers' job was to study the code and extract from it the original message, or "cleartext." The NSA had called Becker because they suspected the original message was written in Mandarin Chinese; he was to translate the symbols as the cryptographers decrypted them.

For two hours, Becker interpreted an endless stream of Mandarin symbols. But each time he gave them a translation, the cryptographers shook their heads in despair. Apparently the code was not making sense. Eager to help, Becker pointed out that all the characters they'd shown him had a common trait-they were also part of the Kanji language. Instantly the bustle in the room fell silent. The man in charge, a lanky chain-smoker named Morante, turned to Becker in disbelief.

"You mean these symbols have multiple meanings?"

Becker nodded. He explained that Kanji was a Japanese writing system based on modified Chinese characters. He'd been giving Mandarin translations because that's what they'd asked for.

"Jesus Christ." Morante coughed. "Let's try the Kanji."

Like magic, everything fell into place.

The cryptographers were duly impressed, but nonetheless, they still made Becker work on the characters out of sequence. "It's for your own safety," Morante said. "This way, you won't know what you're translating."

Becker laughed. Then he noticed nobody else was laughing.

When the code finally broke, Becker had no idea what dark secrets he'd helped reveal, but one thing was for certain-the NSA took code-breaking seriously; the check in Becker's pocket was more than an entire month's university salary.

On his way back out through the series of security check points in the main corridor, Becker's exit was blocked by a guard hanging up a phone. "Mr. Becker, wait here, please."

"What's the problem?" Becker had not expected the meeting to take so long, and he was running late for his standing Saturday afternoon squash match.

The guard shrugged. "Head of Crypto wants a word. She's on her way out now."

"She?" Becker laughed. He had yet to see a female inside the NSA.

"Is that a problem for you?" a woman's voice asked from behind him.

Becker turned and immediately felt himself flush. He eyed the ID card on the woman's blouse. The head of the NSA's Cryptography Division was not only a woman, but an attractive woman at that.

"No," Becker fumbled. "I just..."

"Susan Fletcher." The woman smiled, holding out her slender hand.

Becker took it. "David Becker."

"Congratulations, Mr. Becker. I hear you did a fine job today. Might I chat with you about it?"

Becker hesitated. "Actually, I'm in a bit of a rush at the moment." He hoped spurning the world's most powerful intelligence agency wasn't a foolish act, but his squash match started in forty-five minutes, and he had a reputation to uphold: David Becker was never late for squash... class maybe, but never squash.

"I'll be brief." Susan Fletcher smiled. "Right this way, please."

Ten minutes later, Becker was in the NSA's commissary enjoying a popover and cranberry juice with the NSA's lovely head cryptographer, Susan Fletcher. It quickly became evident to David that the thirty-eight-year-old's high-ranking position at the NSA was no fluke-she was one of the brightest women he had ever met. As they discussed codes and code-breaking, Becker found himself struggling to keep up-a new and exciting experience for him.

An hour later, after Becker had obviously missed his squash match and Susan had blatantly ignored three pages on the intercom, both of them had to laugh. There they were, two highly analytical minds, presumably immune to irrational infatuations-but somehow, while they sat there discussing linguistic morphology and pseudo-random number generators, they felt like a couple of teenagers-everything was fireworks.

Susan never did get around to the real reason she'd wanted to speak to David Becker-to offer him a trial post in their Asiatic Cryptography Division. It was clear from the passion with which the young professor spoke about teaching that he would never leave the university. Susan decided not to ruin the mood by talking business. She felt like a schoolgirl all over again; nothing was going to spoil it. And nothing did.

Their courtship was slow and romantic-stolen escapes whenever their schedules permitted, long walks through the Georgetown campus, late-night cappuccinos at Merlutti's, occasional lectures and concerts. Susan found herself laughing more than she'd ever thought possible. It seemed there was nothing David couldn't twist into a joke. It was a welcome release from the intensity of her post at the NSA.

One crisp, autumn afternoon they sat in the bleachers watching Georgetown soccer get pummeled by Rutgers.

"What sport did you say you play?" Susan teased. "Zucchini?"

Becker groaned. "It's called squash."

She gave him a dumb look.

"It's like zucchini," he explained, "but the court's smaller."

Susan pushed him.

Georgetown's left wing sent a corner-kick sailing out of bounds, and a boo went up from the crowd. The defensemen hurried back downfield.

"How about you?" Becker asked. "Play any sports?"

"I'm a black belt in Stairmaster."

Becker cringed. "I prefer sports you can win."

Susan smiled. "Overachiever, are we?"

Georgetown's star defenseman blocked a pass, and there was a communal cheer in the stands. Susan leaned over and whispered in David's ear. "Doctor."

He turned and eyed her, lost.

"Doctor," she repeated. "Say the first thing that comes to mind."

Becker looked doubtful. "Word associations?"

"Standard NSA procedure. I need to know who I'm with." She eyed him sternly. "Doctor."

Becker shrugged. "Seuss."

Susan gave him a frown. "Okay, try this one... 'kitchen.' "

He didn't hesitate. "Bedroom."

Susan arched her eyebrows coyly. "Okay, how about this... 'cat.' "

"Gut," Becker fired back.

"Gut?"

"Yeah. Catgut. Squash racquet string of champions."

"That's pleasant." She groaned.

"Your diagnosis?" Becker inquired.

Susan thought a minute. "You're a childish, sexually frustrated squash fiend."

Becker shrugged. "Sounds about right."

It went on like that for weeks. Over dessert at all-night diners Becker would ask endless questions.

Where had she learned mathematics?

How did she end up at the NSA?

How did she get so captivating?

Susan blushed and admitted she'd been a late bloomer. Lanky and awkward with braces through her late teens, Susan said her Aunt Clara had once told her God's apology for Susan's plainness was to give her brains. A premature apology, Becker thought.

Susan explained that her interest in cryptography had started in junior high school. The president of the computer club, a towering eighth grader named Frank Gutmann, typed her a love poem and encrypted it with a number-substitution scheme. Susan begged to know what it said. Frank flirtatiously refused. Susan took the code home and stayed up all night with a flashlight under her covers until she figured out the secret-every number represented a letter. She carefully deciphered the code and watched in wonder as the seemingly random digits turned magically into beautiful poetry. In that instant, she knew she'd fallen in love-codes and cryptography would become her life.

Almost twenty years later, after getting her master's in mathematics from Johns Hopkins and studying number theory on a full scholarship from MIT, she submitted her doctoral thesis, Cryptographic Methods, Protocols, and Algorithms for Manual Applications. Apparently her professor was not the only one who read it; shortly afterward, Susan received a phone call and a plane ticket from the NSA.

Everyone in cryptography knew about the NSA; it was home to the best cryptographic minds on the planet. Each spring, as the private-sector firms descended on the brightest new minds in the workforce and offered obscene salaries and stock options, the NSA watched carefully, selected their targets, and then simply stepped in and doubled the best standing offer. What the NSA wanted, the NSA bought. Trembling with anticipation, Susan flew to Washington's Dulles International Airport where she was met by an NSA driver, who whisked her off to Fort Meade.

There were forty-one others who had received the same phone call that year. At twenty-eight, Susan was the youngest. She was also the only female. The visit turned out to be more of a public relations bonanza and a barrage of intelligence testing than an informational session. In the week that followed, Susan and six others where invited back. Although hesitant, Susan returned. The group was immediately separated. They underwent individual polygraph tests, background searches, handwriting analyses, and endless hours of interviews, including taped inquiries into their sexual orientations and practices. When the interviewer asked Susan if she'd ever engaged in sex with animals, she almost walked out, but somehow the mystery carried her through-the prospect of working on the cutting edge of code theory, entering "The Puzzle Palace," and becoming a member of the most secretive club in the world-the National Security Agency.

Becker sat riveted by her stories. "They actually asked you if you'd had sex with animals?"

Susan shrugged. "Part of the routine background check."

"Well..." Becker fought off a grin. "What did you say?"

She kicked him under the table. "I told them no!" Then she added, "And until last night, it was true."

In Susan's eyes, David was as close to perfect as she could imagine. He only had one unfortunate quality; every time they went out, he insisted on picking up the check. Susan hated seeing him lay down a full day's salary on dinner for two, but Becker was immovable. Susan learned not to protest, but it still bothered her. I make more money than I know what to do with, she thought. I should be paying.

Nonetheless, Susan decided that aside from David's outdated sense of chivalry, he was ideal. He was compassionate, smart, funny, and best of all, he had a sincere interest in her work. Whether it was during trips to the Smithsonian, bike rides, or burning spaghetti in Susan's kitchen, David was perpetually curious. Susan answered what questions she could and gave David the general, unclassified overview of the National Security Agency. What David heard enthralled him.

Founded by President Truman at 12:01 a.m. on November 4, 1952, the NSA had been the most clandestine intelligence agency in the world for almost fifty years. The NSA's seven-page inception doctrine laid out a very concise agenda: to protect U.S. government communications and to intercept the communications of foreign powers.

The roof of the NSA's main operations building was littered with over five hundred antennas, including two large radomes that looked like enormous golf balls. The building itself was mammoth-over two million square feet, twice the size of CIA headquarters. Inside were eight million feet of telephone wire and eighty thousand square feet of permanently sealed windows.

Susan told David about COMINT, the agency's global reconnaissance division-a mind-boggling collection of listening posts, satellites, spies, and wiretaps around the globe. Thousands of communiques and conversations were intercepted every day, and they were all sent to the NSA's analysts for decryption. The FBI, CIA, and U.S. foreign policy advisors all depended on the NSA's intelligence to make their decisions.

Becker was mesmerized. "And code-breaking? Where do you fit in?"

Susan explained how the intercepted transmissions often originated from dangerous governments, hostile factions, and terrorist groups, many of whom were inside U.S. borders. Their communications were usually encoded for secrecy in case they ended up in the wrong hands-which, thanks to COMINT, they usually did. Susan told David her job was to study the codes, break them by hand, and furnish the NSA with the deciphered messages. This was not entirely true.

Susan felt a pang of guilt over lying to her new love, but she had no choice. A few years ago it would have been accurate, but things had changed at the NSA. The whole world of cryptography had changed. Susan's new duties were classified, even to many in the highest echelons of power.

"Codes," Becker said, fascinated. "How do you know where to start? I mean... how do you break them?"

Susan smiled. "You of all people should know. It's like studying a foreign language. At first the text looks like gibberish, but as you learn the rules defining its structure, you can start to extract meaning."

Becker nodded, impressed. He wanted to know more.

With Merlutti's napkins and concert programs as her chalkboard, Susan set out to give her charming new pedagogue a mini course in cryptography. She began with Julius Caesar's "perfect square" cipher box.

Caesar, she explained, was the first code-writer in history. When his foot-messengers started getting ambushed and his secret communiques stolen, he devised a rudimentary way to encrypt this directives. He rearranged the text of his messages such that the correspondence looked senseless. Of course, it was not. Each message always had a letter-count that was a perfect square-sixteen, twenty-five, one hundred-depending on how much Caesar needed to say. He secretly informed his officers that when a random message arrived, they should transcribe the text into a square grid. If they did, and read top-to-bottom, a secret message would magically appear.

Over time Caesar's concept of rearranging text was adopted by others and modified to become more difficult to break. The pinnacle of non computer-based encryption came during World War II. The Nazis built a baffling encryption machine named Enigma. The device resembled an old-fashioned typewriter with brass interlocking rotors that revolved in intricate ways and shuffled cleartext into confounding arrays of seemingly senseless character groupings. Only by having another Enigma machine, calibrated the exact same way, could the recipient break the code.

Becker listened, spellbound. The teacher had become the student.

One night, at a university performance of The Nutcracker, Susan gave David his first basic code to break. He sat through the entire intermission, pen in hand, puzzling over the eleven-letter message:

HL FKZC VD LDS

Finally, just as the lights dimmed for the second half, he got it. To encode, Susan had simply replaced each letter of her message with the letter preceding it in the alphabet. To decrypt the code, all Becker had to do was shift each letter one space forward in the alphabet-"A" became "B," "B" became "C," and so on. He quickly shifted the remaining letters. He never imagined four little syllables could make him so happy:

IM GLAD WE MET

He quickly scrawled his response and handed it to her:

LD SNN

Susan read it and beamed.

Becker had to laugh; he was thirty-five years-old, and his heart was doing back flips. He'd never been so attracted to a woman in his life. Her delicate European features and soft brown eyes reminded him of an ad for Estee Lauder. If Susan's body had been lanky and awkward as a teenager, it sure wasn't now. Somewhere along the way, she had developed a willowy grace-slender and tall with full, firm breasts and a perfectly flat abdomen. David often joked that she was the first swimsuit model he'd ever met with a doctorate in applied mathematics and number theory. As the months passed, they both started to suspect they'd found something that could last a lifetime.

They'd been together almost two years when, out of the blue, David proposed to her. It was on a weekend trip to the Smoky Mountains. They were lying on a big canopy bed at Stone Manor. He had no ring-he just blurted it out. That's what she loved about him-he was so spontaneous. She kissed him long and hard. He took her in his arms and slipped off her nightgown.

"I'll take that as a yes," he said, and they made love all night by the warmth of the fire.

That magical evening had been six months ago-before David's unexpected promotion to chairman of the Modern Language Department. Their relationship had been in a downhill slide ever since.