“It’s a scanning corridor. Just to make sure you’re not bringing anything in or out. The instruments, software, information, everything on the inside must stay inside.”

“Everything?”

“Everything except a few tightly controlled datastreams.”

“But all the real processing takes place here, on the inside. Right? There must be an outrageous amount of number-crunching going on.”

“More than you could ever imagine.” Mauchly pointed at a large panel, set low into one wall. “Data conduits like this link all the areas inside the Wall. They’re basically wiring trunks that connect every internal system to all the others.”

Mauchly stepped to one side and gestured toward a figure Lash had not noticed before. “This is Tara Stapleton, our chief security technician. She’ll be your advisor while you’re inside.”

The woman stepped forward. “Dr. Lash,” she said in low, quiet voice, extending her hand.

Lash took it. Stapleton was a tall brunette with serious eyes who, he decided, couldn’t yet have reached thirty.

“Our first stop is this way,” Mauchly said as they started down one of the wide corridors. “Tara has just been briefed on exactly why you’re here. But of course nobody else knows. Your cover story’s that you’re preparing an efficiency report for the board’s five-year plan. I think you’ll be surprised at just how dedicated, and motivated, our people are.”

Lash glanced at Tara Stapleton. “Is that true?”

She nodded. “We have all the best equipment. We have a proprietary technology far beyond anything else. What other job lets you make such a difference in other people’s lives?” Despite the enthusiastic words, the delivery seemed rote, without nuance, as if her mind was elsewhere.

“Remember those class reunions I had you listen in on?” Mauchly asked. “Everyone on staff is required to witness them twice a year. It helps remind us of what we’re working for.”

They had arrived at a set of double doors labeled DATA GATHERING — INTERNET — GALLERY. Mauchly placed his bracelet beneath the scanner and the doors slid back. He motioned Lash ahead.

Lash found himself on a balcony above a room busy as the trading floor of the New York Stock Exchange. Except that, while the Stock Exchange always seemed to Lash like barely contained chaos, the huge space below had the precise, calm flow of a beehive. People sat at desks, staring at computer screens, while others gathered at data centers, pointing up at monitors or speaking into telephones. Oversize videoscreens covered the walls, showing feeds from Reuters and other wire services, CNN, local and foreign newscasts.

“This is one of our data-gathering centers,” Mauchly said. “There are several other research and surveillance subsections in the building, all similar to this one.”

“It seems like an awfully big operation,” Lash murmured as he gazed at the activity below.

“We tell our clients their single day of testing is the most important stage in the matching process, but actually it’s just a small part. Following the evaluation, we monitor all aspects of an applicant’s behavior patterns. It can take a few days, or a month, depending on the width of the datastream we get back. Lifestyle preferences, taste in clothes and entertainment, spending habits: everything is tracked. For example, this center tracks an applicant’s Internet use. We monitor what sites are visited, how they’re moused, then we integrate the clickstream data with the other information we’re gathering.”

Lash looked at him. “How is that possible?”

“We have agreements with the major credit agencies, telephone and ISP providers, cable and satellite TV, and the like. They allow us to monitor their bandwidth. And we in turn provide them with certain metrics — generalized, of course — for spotting trends. And we have our own surveillance specialists on board, of course. The omnipresence of computers in daily life is part of what makes our business possible, Dr. Lash.”

“Makes me almost afraid to touch mine,” Lash said.

“All monitoring is transparent. Our clients have no idea their Web surfing, credit card charges, and phone records are being tracked. It gives us a far more complete picture than we could gather any other way. It’s one of the things that separates us from the other, far more primitive social-networking services that have sprung up in our wake. And needless to say, the data we gather remains within these walls. That’s another reason why we seem so secretive to you, Dr. Lash: our first mandate is to ensure our clients’ privacy.”

He waved his hand at the activity below. “Once the Thorpes completed their personal evaluations, their datafiles would have been distributed to centers like this for monitoring. It would have been the same for the Wilners. Or you, for that matter, had you been selected as a candidate.”

Here, Mauchly paused. “By the way, I’m sorry about that. I’ve read the exit reports of Vogel and Alicto.”

“Your Dr. Alicto seemed to have a personal grudge against me.”

“No doubt it seemed that way. The senior examiner does have some leeway in how he conducts an interview. Alicto is one of our best examiners, but he’s also one of the most unorthodox. In any case, it was not a real evaluation in the sense that you were a candidate. I hope that lessens the sting somewhat.”

“Let’s move on.” Lash felt vaguely uncomfortable about having his less-than-stellar performance analyzed before Tara Stapleton.

Mauchly ushered Lash out of the gallery and down the long, pale-hued corridor, stopping at last before a heavy steel door marked by a biohazard symbol and the label RADIOLOGY AND GENETICS III. Once again, Mauchly opened the door with his security bracelet. Beyond was a large room full of gray-painted lockers. “Bluesuits” for biomedical and hazmat duty hung from metal dollies. The far wall of the room was made of clear Plexiglas, and its sealed entrance portal sported several warnings. Clean-Room Environment Beyond, read one; Sterile Clothing and Procedures MANDATORY. Thank You For Your Cooperation.

Lash walked up to the glass and looked through curiously. He could see gloved and suited figures bending over a variety of complex equipment.

“That looks like a DNA sequencer,” he said, pointing at a particularly large console in a far corner.

Mauchly came up beside him. “It is.”

“What’s it doing here?”

“Part of our genetics analysis.”

“I don’t see what genetics has to do with a service like yours.”

“Many things, actually. It’s one of Eden’s most sensitive areas of research.”

Lash waited expectantly, letting the silence lengthen. At last, Mauchly sighed.

“As you know, our application process isn’t limited to psychological evaluations. During the initial physical, any candidates who present with significant physical problems, or appear to be at high risk for future problems, are disqualified.”

“Seems harsh.”

“Not at all. Would you care to meet your perfect mate, only to have her die a year later? In any case, after the physical, the candidate’s blood is further screened — here and at other labs inside the Wall — for a variety of genetic disorders. Anybody with a genetic predisposition for Alzheimer’s, cystic fibrosis, Huntington’s chorea, and such are also disqualified.”

“Jesus. Do you tell them why?”

“Not directly, no — it might attract attention to our trade secrets. Besides, rejection can be traumatizing enough. Why compound it with anxiety over something that might not develop for years — if at all — and that’s untreatable in any case?”

Why, indeed? Lash thought.

“But that’s just the beginning. Our most important use of genetics comes in the matching process itself.”

Lash looked from Mauchly, to the lab workers moving busily beyond the Plexiglas wall, and back to Mauchly again.

“You’re no doubt more familiar with evolutionary psychology than I am,” Mauchly said. “In particular, the concept of gene spreading.”