Gideon thought back to their conversation in the restaurant. "Something she'd need a Daedalus for," he muttered.
"What?"
"What if they were watching us, had a man near us? What if something we did or said triggered the attack? What if we stumbled on something the IUF didn't want anyone to know?"
"Like what? We just talked about Julie's life, nothing secret—" Ruth shivered a little bit. "We didn't talk about anything worth shooting at us for."
Gideon stared out at a platform as the train pulled out. The lighted platform slid away and replaced itself with the depthless black of the tunnels. The clearest image was his own reflection in the window.
"She was working on something on her own. Something private. Everyone looking for Julia Zimmerman is afraid of what she was known to be working on for the NSA. What if the IUF offered her the opportunity to work on something she couldn't work on at the NSA?"
Ruth shook her head. "I know where you're going with that. I know it looks a lot like when she left MIT. But Julie isn't stupid. She'd consider the consequences of her actions. She knew that she could screw MIT, because she knew who would be backing her if things came to a head. She knew that she'd beat them." She turned her head and looked at Gideon. "This isn't the same. I can't see her making that decision. This is a no-win situation."
The train pulled to a stop again, and Gideon stood up. "Come on."
"What? Where are we going?"
"I want to make a stop at the library."
When Gideon sat behind one of the public terminals at the New York Public Library, Ruth asked him, "And what exactly do you expect to find here?"
Gideon cued up a search engine and said, "I want to look into what your sister might have been working
on."
"How the hell do you intend to do that?" Ruth pulled up a chair and sat next to him. "Are you some sort of police mathematician?"
"No," Gideon shook his head. "But I think the answer is somewhere in what we already know."
There was a pile of scratch paper and a small pencil box next to the computer. He took a sheet and a pencil and started scribbling a list of words;
"Information Warfare. Virus. Cryptography. Riemann. Number Theory. Aleph-Null. Evolutionary Algorithm. Zeta Function."
Gideon looked at the list of words. "That should be enough of a start."
Ruth watched as he scanned papers, articles, as well as the other detritus accumulated on the Internet. Those sites that weren't mathematical tended to be about private-sector information security. After about fifteen minutes, Gideon found a page that made him realize one of the fundamental reasons why the government was scared of losing Zimmerman. On the screen was a layman's description of public key cryptography, the de facto standard for secure personal communications on the Internet.
"No wonder they're frightened of her," Gideon whispered.
"What?" Ruth said.
"Look at this." Gideon tapped his finger on a paragraph that he had just scrolled onto the screen. "This whole process is based on very large prime numbers. . ."
"Okay, so?"
"That was at the heart of what she was doing at MIT, wasn't it?"
Ruth shrugged. "I never followed it very well. She was way past me by the time she left grade school."
Gideon scrolled through the article. "Most of the security on the Internet is based on these huge numbers, and on the fact that it's supposedly a practical impossibility to factor a four-thousand-bit number by brute force."
"So?"
"I'm not a mathematician, but one of the things that your sister's colleague, Dr. Nolan, told me—'Zimmerman was pushing the lab toward new theorems that could generate the primes, or factor huge numbers.'" Gideon shook his head. "No wonder the NSA wanted her, and wants her back. With that kind of algorithm there'd be no such thing as a secure communication on the Internet—or elsewhere for that matter. E-mail, credit-card transactions, private databases—you could crack any of it, all of it."
Ruth stared at the screen. "Do you think she managed that?"
"Why not?" Gideon said. "What would be worth more to an intelligence gathering agency? A factoring algorithm that renders the bulk of encrypted information in existence completely transparent." Gideon nodded to himself, leaning back. "And they have to be very careful bringing her back. If it became public knowledge that such an algorithm existed, it would become useless." Gideon tapped his fingers on the table. "That explains the government. . ."
Gideon was quiet a long while before Ruth interrupted him. "You don't sound completely sure."
Gideon shook his head. "I can make it fit with everything . . . except your sister. It fits with what the old man said about her designing parts of the NSA's computer security—" He sighed. "There's more to this. I know there's more to this. This doesn't explain why your sister disappeared. It certainly doesn't explain why she, or the IUF, would need a supercomputer."
"It doesn't? This sounds kind of heavy to me."
Gideon nodded. "But the work she was doing at MIT was using equipment anyone has access to, not particularly sophisticated. 200Mhz PCs. I could get more powerful computers used. So, if what she did was a direct outgrowth of the ET Lab, why would she suddenly need the kind of power a Daedalus provides? Not to mention, this is exactly the kind of thing the NSA was using her for. I'm sure that whatever she's doing now would have to be something that she couldn’t do at the NSA—"
"I keep telling you. She's not stupid. She wouldn't jump ship at the NSA unless she thought the odds were in favor of her getting away with it.
Gideon nodded. He'd been thinking along those lines himself. There was another possibility that Ruth wasn't seeing. What if Zimmerman didn't care about the odds? What if she was working on something that she thought was important enough to risk being hunted down by the Feds as a traitor?
There wasn't any question in Gideon's mind that Zimmerman had her own agenda. What if there was something she was working on in secret, ever since MIT? Maybe since before . . .
But what?
What could she think is that important?
Gideon stared at the screen, trying to think. Ruth looked at him and said, "Don't you think it's time to consider the FBI?"
Gideon looked at Ruth. "I doubt the government's priorities match ours— I don't think they care about bringing your sister in alive."
"And you do?"
The question made Gideon uncomfortable. He had been driven to this point by a need to discover what had happened in the warehouse, why Rafe had died. Somehow, his focus had changed. Julia Zimmerman had become his focus. He could rationalize it by saying that she had been the focus of what had happened at the warehouse. Was that the real reason? He was following this woman, finding himself fascinated by her history. . .
In his gut he knew that, if he discovered what she was doing, he could damage those who had shot him and killed Rafe. He knew he wanted to bring whatever happened to the press and to that Congressional hearing. He wanted to damage those who had damaged so much around him.
He wanted to vindicate himself.
But that wasn't it. Not completely.
He realized that he didn't want Julia Zimmerman to end like Rafe, or Kendal, or Davy Jones, or Kareem Rashad Williams. Whatever she had done, Gideon had an irrational belief that it wasn't treasonous. Somehow she was serving her first and only love. There was something in her that wasn't of Gideon's world. Gideon's world was constructed from self-serving politics, where his brother's death was some sort of bargaining chip, a political asset—or liability—depending on what side of the fence you were on.
Julia came from somewhere else. And, somehow, understanding her, what she was doing, would give Rafe's death the meaning that Gideon desperately needed. Gideon couldn't accept that all it had been was some interdepartmental screwup. . .