"So Than Rang is a glorified street criminal," Kurt said. "But that doesn't tell us what he wants with computer experts."

"Could be any number of things," Pitt said. "Considering the structure of the chaebol and the intense compet.i.tion in today's world, I'd lay my money on corporate espionage."

"Makes sense," Kurt said. "But the strange woman and her backers seemed to want these people for something else. She talked about breaching the American Wall. She also mentioned something called an air gap. Any idea what those terms mean?"

Pitt looked off the screen. "Hiram, you want to take this one?"

Hiram Yaeger came into view, long hair still in a ponytail, granny gla.s.ses firmly in place.

"Good morning, gentlemen," he said. "I'll get right to it. The term American Wall has been used in cybers.p.a.ce for the last few years. It refers to an elaborate series of firewalls and defenses we've built up to protect the information infrastructure. The thing is, no one is supposed to know about them. These systems are operated exclusively by the NSA. They cover government inst.i.tutions and important civilian corporations."

This took Kurt by surprise. "I keep hearing how vulnerable we are," he said. "Are you saying this isn't the case?"

"Let's put it this way," Hiram said. "We're not as weak as we pretend to be. But the fact that your friend was talking about breaching the wall and bringing the system down suggests they're contemplating something much bigger and deeper than your standard everyday hacking."

"She's not my friend," Kurt said testily, "though she did save my life."

"Odd, that," Pitt said.

"Trust me, that wasn't the only odd part," Kurt said.

Pitt laughed.

"How might Sienna and Phalanx fit into all this?" Kurt asked.

Hiram was blunt. "If Phalanx works, it will replace the existing wall. In effect, it will be the American Wall 2.0."

"What about these hackers?" Joe asked. "Any idea who they are?"

"We're working on it," Hiram said. "Aided and complicated by the fact that hackers have their own naming subculture."

"The woman called them handles," Kurt said.

"Exactly," Hiram replied. "They're more than just random call signs; they mean something. It's a way of getting in touch with the right person. For example, even though Xeno9X9 sounds like a random string of letters and numbers, it actually tells us about the hacker's skills. Xeno meaning 'foreign,' 9X9 being similar to the old radio terminology 'five by five,' meaning 'strong signal, clear signal.' My best guess is that Xeno9X9 is someone who can hack across borders with little problem."

Pitt chimed in. "Based on prodigious amounts of research, we believe he's a Ukrainian named Goshun. Interestingly enough, he went missing over a year ago. The prevailing thought was that he'd gone on the lam because his ident.i.ty had become known. Now we're wondering if Acosta had something to do with it."

Kurt made a mental note of that. "What about the others?"

"We think ZSumG is short for 'zero sum game,' " Hiram said, "a term commonly used in economic and market theories. It means one side can profit only if the other side loses an equal amount."

"One winner, one loser," Joe said. "No way for a win-win outcome."

"Exactly," Hiram said.

"So ZSumG might be a financial hacker?" Kurt asked.

"That's our thought," Hiram said. "Based on the evidence, ZSumG is believed to have cracked the security of several major banks in the last five years, stealing millions of credit card numbers, ident.i.ty profiles, and bank account pins. He then sold them to criminal groups around the world."

"Sounds like a lovely guy," Joe said.

"Or gal," Hiram said. "We're not sure. Which brings us to the last name: Montresor."

"Why does that sound familiar?" Joe asked.

Kurt had been thinking the same thing. The answer had come to him this morning. "Not keeping up on your required reading," he said to his friend.

"I wait till the end of summer break," Joe replied. "And then I cram it all in at the last minute."

Kurt laughed lightly and then spoke. " 'The thousand injuries of Fortunato I had borne as best I could,' " he said. " 'But when he ventured upon insult, I vowed revenge.' "

" 'The Cask of Amontillado,' " Hiram explained to Joe. "The name comes from the Edgar Allan Poe cla.s.sic."

"So it could be a reference to revenge," Joe suggested.

"Or to hiding things where they can't be found," Kurt guessed, "the way Montresor sealed Fortunato in the wall."

"Or he could be Italian and likes his red wine," Hiram said.

"Might want to check on Giordino," Kurt suggested.

"Don't think we haven't," Pitt said. "Turns out, he's still trying to master s.p.a.ce Invaders on his Commodore 64. So it's probably not him."

Kurt smiled, appreciating the moment of levity, but the fog of war had not lifted. "So we have no real answers," he said, "only more questions."

"What about the Ma.s.sif ?" Joe asked hopefully.

"We tracked her on satellite," Pitt said. "She's put into Bandar Abbas for repairs. Probably in need of a new propeller shaft. But since she's in Iranian waters, there's not much we can do to get a look at her."

"I'd guess all the big shots on board are long gone by now," Kurt said.

"Which puts us back to square one," Pitt added, taking center stage again. "We know there's some kind of hacker dream team for sale or rent out there, and at least two groups fighting over them. But we don't know why. And we're pretty certain neither group are the kind of players we'd like to be at the mercy of."

"Then we have only one choice," Kurt said. "To short-circuit both threats simultaneously."

"And how do you propose to do that?" Pitt asked.

"We go to South Korea and get this 'American woman' and the other hackers back. As long as they're in our hands, no one can use them against us."

On the top floor of the NUMA building in Washington, Dirk Pitt and Hiram Yaeger sat on one side of the communications console. Kurt and Joe had just signed off.

Pitt decided it was time to get the temperature of the room. "Well," he said, "what do you think?"

Across from him, out of sight and silent during the call, sat Trent MacDonald of the CIA, a man named Sutton from the NSA, and two others from NUMA: Dr. Elliot Smith, who'd become NUMA's chief medical officer, and Anna Ericsson.

Pitt didn't like speaking to Kurt with these observers watching from the shadows like some kind of judging committee, but considering how the stakes were rising, it needed to be done.

Dr. Smith spoke first. "Kurt looks stable. His affect is normal and he's not reporting any symptoms."

"That's good," Pitt said.

Smith gave a noncommittal shrug. "It is, except that symptoms like Kurt's shouldn't just vanish because he got away from Washington."

"I've always found leaving this place cures a few ills," Yaeger added, clearly hoping Kurt was on the road to recovery. "Maybe," Smith said, "but not the kind Kurt had." Pitt jumped in. He wanted concrete statements, not vague a.s.sertions. "Meaning what?"

"I'd say we can expect his symptoms to return at some point.

Most likely, under a moment of extreme duress."

"Ms. Ericsson?" Pitt asked.

"He looks well to me. Better than he did when he was cooped up back here."

"What about his story?" Sutton asked.

"What about it?" Pitt said.

"Seems a little odd, don't you think? He got on board the yacht, found something extremely vague, was attacked, and then was rescued by this strange mystery woman. He supposedly got her satellite phone but lost it. Gave us a poor description. All things we have to take on faith."

"You think he was making that up?"

"That's just it," Sutton said. "He was the only one there. So we can't prove it one way or another."

"What about the call she made?" Pitt asked.

"We've been trying to determine if that happened," Sutton admitted. "No luck yet."

"It could have been foreign service," Hiram pointed out, "someone you don't have access to."

"We have access to everyone," Sutton a.s.sured him.

"Trust me."

"What about the names of those hackers?" Pitt asked. "He didn't just pluck them out of thin air."

Sutton shrugged. He had no comeback to that.

"Now for the elephant in the room," Pitt said. "We know where Sutton stands. He thinks this is all one big delusion. But what does it mean if Kurt's actually onto something?"

Trent MacDonald wrung his hands for a second. Pitt noted that the CIA rep had been awfully quiet.

"Trent?"

"If he's onto something, if Sienna Westgate is alive and in the hands of foreign nationals or persons unknown, then we may have a bigger problem than any of us know. At the very least, we should let Kurt continue and look into this Than Rang character. With a little prodding, I might be able to pledge some help. We have a lot more a.s.sets on the Korean Peninsula than we do in Iran."

Dirk nodded quietly. He couldn't recall a time he'd gotten so much cooperation from the CIA. He wondered if it had something to do with Kurt's history there or, for that matter, with Sienna's. A thought formed in his mind. "Is Sienna Westgate still working for the CIA?"

MacDonald did not reply immediately. "In a manner of speaking," he said finally. "Sienna legitimately left the Agency eight years ago. We didn't want to lose her when she went private, but we couldn't compete with a guy like Westgate and all he had to offer."

"Go on," Pitt said.

"She was brilliant," MacDonald said, nodding to Hiram. "You've seen her work."

"A savant," Yaeger said. "And I mean that as the highest compliment I can give."

"Exactly," MacDonald said. "So we made a deal with her and Westgate. We gave them the beginnings of our most advanced theoretical system and asked them to build it into an unbreakable barrier."

"Which she turned into Phalanx," Pitt said.

MacDonald nodded.

"But you never expected it to get out of the bottle," Yaeger pointed out.

"No," MacDonald said. "And that possibility is daunting for two reasons. One, we're going to lose a lot of intelligence- gathering ability if the rest of the world co-opts Phalanx and keeps us from prying into their systems. But there's a bigger worry, one we don't know how to quantify."

"Which is?"

"We all believe that Phalanx is unbreakable. We've installed it on everything from the DOD computer network to the Social Security database, but no one knows as much about it as Sienna Westgate. She was the lead designer of the project, she was the only one entrusted with the technology we gave her, and she took it ten steps beyond. That means she knows its weaknesses better than anyone. She might even have designed a back door into the system in case she ever needed to use it. We have no way of knowing."

Pitt was beginning to understand. "And Phalanx is now protecting the entire federal government."

MacDonald nodded. Sutton did likewise.

"Maybe we should pull Phalanx off active duty," Pitt suggested.

"It's being considered," Sutton said. "But it would be premature and foolish to do so based on what we know at this point. We need proof one way or the other before we act."

MacDonald summed up. "I don't know if she's out there and in the hands of our would-be enemies," he said. "But as much as I hate to say it, I'd be a lot happier knowing for certain that she'd been dragged to the bottom of the sea and drowned."

As cold as the statement was, Pitt understood the thought. "Then we'd better get a team down to what's left of Westgate's sunken yacht," he said bluntly. "It's a long shot, considering the condition of the vessel. But if we find Sienna's body, then you guys can rest easy. And I can bring Kurt home."

The NUMA vessel Condor sat calmly on a glittering sea two hundred miles northeast of the South African port city of Durban. The sun was high above and there wasn't a cloud in the sky. The sea was like gla.s.s.

With no weather on the horizon and the automated station system holding the Condor against the current and keeping her over the proper coordinates, there was little activity on the bridge.

The aft deck was a different story. A dozen men and women were cl.u.s.tered around a pair of davits as twin submersibles were being readied for launch.

The subs were called Scarabs, because they resembled the beetles of Egyptian legend. Instead of narrow and tube-shaped, like most submersibles, the Scarabs were flat and wide. They had a large bulbous front, made entirely of three-inch-thick clear polymer, and a rear compartment that tapered to a point, filled with equipment, battery packs, and ballast tanks. Thruster pods housed in short tubes on either side of the body looked like stubby legs, and a pair of large mechanical arms that sprouted from beneath the nose, carrying sampling probes and grabbing appendages, were reminiscent of a beetle's pincerlike claws.

Scarab One was the older model, painted international orange, the color of life jackets. Scarab Two was bright yellow, the color commonly a.s.sociated with experimental submersibles. It had come from the factory only a month before, equipped with more power, newer, longer-lasting batteries, and an advanced touchscreen control system.

Standing one deck above the busy crewmen, Paul Trout watched with great interest as the subs were readied for operations, though he had no intention of going down in either of them.

Paul was the size and shape of a professional basketball player, though even he would admit not as coordinated or athletically gifted. What he lacked in sporting skills Paul made up for with a brilliant mind. A gifted geologist, he and his wife, Gamay, were often called on to run NUMA's most important scientific studies. While he excelled in geology, Gamay had a Ph.D. in marine biology and had made several important discoveries of previously unknown species.

Paul realized this latest mission would not offer such a positive find.

"Hey, Paul, care to join me?"