Note: You know that feeling when you find that someone compromised your e-mail account and used it to send advertisements for instant, massively enlarged no-no pipes? What if you had twelve computers and found they'd all been compromised?

The show never really talks about the ethics of hacking...

An IDS is an Intrusion Detection System. They tend to analyze log files for strange errors and keep a list of what critical system files have been changed. They often send out e-mail alerts. I figure Elizabeth has a central e-mail server at her apartment to keep track of the chatter from all of her computers.

Thank you all for all the kind reviews! (And unkind ones, but I haven't gotten any yet.)

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Two Years Prior

Bobby Tam's eyes looked like they were about to pop out of his head. He backed towards the door, but it had swung shut, and there was no handle on the exterior. His back met the solid metal surface. He stuttered and gasped—a natural reaction to being cornered and having a gun shoved in one's face.

"Elizabeth—just—w-what—"

"You bastard," she said. "How could you do this to me?"

"I d-d-don't know what you're talking about," Bobby said.

Elizabeth's hands shook around the gun. The barrel wavered wildly; if she fired now, there was good chance she would miss Bobby Tam entirely. Reese's gun, on the other hand, was as steady as steel. He aimed through the gap between the dumpster and the wall, pointing the gun at Elizabeth's left knee.

Finch's tinny voice was frantic. "Mr. Reese? What's going on?"

"Elizabeth has Bobby Tam at gunpoint, Finch," Reese whispered. He clicked off the safety, but kept his finger away from the trigger.

"How long did you think it would take for me to find it?" Elizabeth said to Bobby.

"F-f-f-f-find what?"

"I had twenty-one thousand messages in my intranet mailbox last night. Seventeen-fucking-thousand alert messages from my IDS. Another four thousand from the network monitor. Did you think you could hide it?"

"Elizabeth, this h-h-has to be some sort of—misunderstanding."

Holding the gun with one hand, Elizabeth reached into her bag again, felt around, and pulled out the backdoor. The gun wavered even more.

"Recognize this? I found it behind my desk."

Reese exhaled. "Finch, she thinks Tam planted the backdoor."

"Oh dear," Finch said. "Oh, this is not good..."

Elizabeth held it out in front of her. "It's a Raspberry Pi, Tam. A fucking Raspberry Pi. You're always going on about your goddamn embedded computers—"

"It's not mine! Hey, It's not mine! Just b-b-because I use them all the time doesn't mean—"

"I took it apart. I spent hours last night looking through the filesystem last night. It's your code."

"N-n-no!" Tam tried to flatten himself against the wall. "It's not!"

"Shut up!" Elizabeth cried, tightening her hand around the gun. Reese saw tears running down her face.

"Finch," Reese whispered. "I'm so sorry. I may have to shoot Elizabeth." His voice was rough. "I'll try to wound her."

When Harold responded, his words were laden with regret. "Do what you must, Mr. Reese."

Elizabeth shook the backdoor violently in Tam's face. "I went through every file. Everyfile. All the Perl scripts—I know your code, Tam. It's all—concise and efficient and—and you're the only person in the entire goddamn company that doesn't put a single goddamn comment anywhere in the source code."

"It's not mine!"

"What did you want? What were you looking for, huh? Why did you have to compromise every single one of my computers?"

"I—"

"What, did you think you'd have a little fun? Twist the knife?"

"Elizabeth, please—why would I—"

"I have to format every single one of my computers because of you," she wailed. "You broke into my network. You broke into my apartment. You screwed with my computers, you violated my privacy, my sense of security—you—you—you—"

Reese rested his lightly finger on the trigger. Every fiber in his being was focused on Elizabeth Ruben. He was poised, under tension, like a bow string pulled back to the max; ready to make the split-second decision to fire and yet praying it wouldn't be necessary to disable the woman.

"Elizabeth," Tam said, his voice trembling as though someone was shaking him by the shoulders. "Look, if I wanted to hack your network, I wouldn't need that thing! You gave me a key for your wireless network, remember? Three months ago."

The sudden wave of confusion and regret that crossed Elizabeth's face told Reese that she didn't.

"You know I wouldn't do something like this," Tam said. His chest heaved. "Never."

Elizabeth lowered the gun, just a little bit. Then a little bit further, and a little more, until the gun was pointed at the ground. It dangled from her fingers, swaying gently back and forth. She didn't say anything. Neither did Tam.

Elizabeth grimaced. Suddenly, she threw the backdoor as hard as she could. It hit the wall a few feet away from Tam and shattered into plastic shards and circuit boards. Tam winced and ducked away. Elizabeth looked like she was about to faint.

"Shit," she said shakily. She began to laugh, but it was not a pretty sound. She wiped her eyes with one hand. "I—I'm sorry, Bobby. I—I thought—if I scared you enough—"

Tam held up his hands. "Trust me, I'm scared, I'm scared!"

"It's not loaded." Elizabeth said, looking down at the gun. "Didn't bring a clip. I don't think it even shoots anymore."

Reese sighed in relief and took his finger from the trigger. He kept his weapon drawn, just in case.

Elizabeth wiped her eyes again and said, "I'm—I'm going h-home." She backed towards her car on unstable legs.

Bobby Tam stared after her, frozen, mouth agape. He didn't find his voice until Elizabeth had her hand on the car door.

"Elizabeth, wait!" he said. "Tell me what happened. Do you need help?"

She shook her head. "I need sleep," she said. Her voice broke. "And them I need to format every fucking one of my computers."

She slammed the door shut, started the engine, and drove off, leaving Tam to stare after her.

Reese let out a long, deep breath. "It's alright, Finch," he whispered, lowering the gun. "It's alright. She's leaving. The gun wasn't loaded."

"Oh, thank goodness," said Finch.

Reese slipped away before Bobby Tam could spot him.

#####

An hour later, Reese and Finch were sitting on a park bench beneath a massive maple tree across the street and a little ways down from the apartment complex. Bear was curled up at John's feet, panting happily in the shade. Reese gazed at Elizabeth's apartment, while Finch's attention was fixed on a silver laptop balanced on his lap. A wireless amplifier had been attached to the back of the laptop lid, connected to the laptop via a USB cable.

"Miss Ruben must have switched off her router entirely when she discovered the backdoor," Finch said. "I detect no trace at all of her wireless network and I can no longer ping her IP address from the Internet. It's a sensible approach, really. When one's system is compromised, the best course of action is to yank all forms of connectivity as soon as possible to isolate the system, then deal with the forensics later."

Reese nodded. A maple leaf fell from the tree and landed on Finch's keyboard. Irritated, Finch brushed it away, then closed the lid and placed his hands on top of it.

"Mr. Reese, I feel responsible for this entire debacle," he said. "I should've realized that Miss Ruben would spot the unusual network traffic and find the extra device attached to her network."

"It was a risk we had to take. We needed more information."

"Yes, Mr. Reese, but now Miss Ruben knows that she is being watched, and we still do not know what the threat against he is, or what harm she intends to cause. We also put her and another individual in harm's way."

Reese looked sideways at Finch. "Can your Machine predict something like that?"

"You mean, could the Machine predict that, by us planting a device in the apartment of someone it already identified as a Number, said Number would go out and put herself or someone out a risk?"

"Yeah."

"Mr. Reese, the Machine cannot deal with circular logic such as this. Say the Machine had been alerting us to a threat against Bobby Tam by Elizabeth Ruben. It would have had to identify Elizabeth Ruben as the threat first. But the threat was caused by us planting the backdoor in Elizabeth Ruben's apartment. We planted the backdoor because we thought Elizabeth Ruben might be a threat. But we thought she might be a threat because the Machine warned us that she might be a threat. The Machine warned us because she was spurred into action by our backdoor, which we planted because—you see? It's a classic circular paradox, Mr. Reese. Utilized quite often in some science-fiction books."

"I never liked science-fiction much," Reese said.

"You should read some, Mr. Reese. There is certainly no shortage of science-fiction books in the Library. I could recommend some classics to you. Gateway, perhaps, or Foundation, or Starship Troopers. The last of which mentions plenty of high-tech firearms and explosives, enough to sate even your voracious appetite for weaponry."

"I'll keep those in mind," Reese said. He returned his attention to Elizabeth Ruben's apartment.

"My instinct says the threat is someone at Landis," Reese said. "I'll put trackers on some of Elizabeth's coworkers' cars tomorrow morning."

"You may as well do it now, Mr. Reese. I suspect Miss Ruben is either sleeping or rebuilding her network from scratch. Either way, she will be occupied for quite some time." Finch frowned. "I regret that we have caused Miss Ruben such inconvenience. Rebuilding a network from scratch is an arduous task. I do hope she keeps good backups."

"If we keep her from getting herself killed, I don't think she'll mind too much." Reese stood. "I'll go plant a few trackers at Landis. Tam, Dodson, and Leroy, for starters."

Finch nodded. Reese scratched Bear behind the ears and walked down the street towards his car.

#####

Harold Finch did not move from that park bench for a very long time.

He wanted to. After a half-hour seated on the hard wood slats, his hip, leg, and spine were all telling him to move, move, move. But he didn't. He stayed, and he watched Elizabeth Ruben's apartment.

Somewhere within the apartment walls, he knew, Elizabeth Ruben was either sleeping or, far more likely, unable to sleep and so dedicating herself to salvaging her network—the network that Finch had compromised and tainted in his efforts to find out as much as possible about the young programmer. Had the situation been reversed, Finch knew he would have responded much as had Miss Ruben (although perhaps minus the gun-waving). He would have worked ceaselessly on repairing the damage, driving himself to an exhaustion-induced stupor before allowing himself to rest, such as he had done when Root had compromised the Library systems. And then, once he woke up again, he would have obsessed on finding the hacker for a long, long time.

But Elizabeth Ruben would never find Harold Finch; of that, he was certain. He had inadvertently sent Miss Ruben on a useless wild-goose chase, arming her with nothing but an IP address halfway across the world.

Although the infiltration was justified—it was always justified in his mind when he broke into someone else's network, so long as there was the possibility to save a life—he still felt regret.

He had moved too fast, used a nuclear-powered depleted-uranium magnetic-drive impulse hammer to drive a nail when a far simpler tool would have sufficed. If only he had taken more time to attempt to derive a key for the wireless network—if only he had used the backdoor as a passive network sniffer instead of infiltrating every computer—if only he had simply had Reese clone the drives and leave. But Finch had been impatient, and entirely too confident in his ability to crack into a mere college intern's homenetwork.

He wondered now if he had resorted to such extreme measures just to prove that he could.

Because of Finch's haste, Elizabeth Ruben had very nearly been shot by John Reese that morning. Because of Finch's impatience, Elizabeth Ruben was forced to purge every device attached to her network: isolating each computer, backing it up, formatting its hard drives, setting up a new operating system, scanning the backup for signs of tampering (hopefully, she had an older set of backups to compare against), and then copying what files she felt were safe back to the formatted disk. It was a tedious, troublesome process, and when combined with the emotional shock of having one's entire network subverted by an unknown third party, the process was an upsetting one. Each computer formatted was a sickly reminder that an unknown had breached the network's security.

John Reese did not understand. To him, computers were mere machines; if one broke, or was compromised, he asked Finch for a replacement, much like an inexpensive cell phone. There was no attachment. But Harold knew just how emotionally devastating it was for one's own network to fall under the control of another hacker. It was a blow to the gut. The revelation that, for all the security measures taken, someone had found a way around them, wormed a way into each computer, and taken up residence at the lowest possible software level, making it impossible to trust the integrity of that computer ever again without a clean format—it destroyed one's sense of security. It was the same emotion one felt after thief broke into one's home, but worse, because there was no way of being sure what had been taken, because files were by their very nature easy to copy to another computer.

Harold Finch was a hacker, one of the finest, if not the finest, in the world. He had brought some of the planet's most complicated networks to their metaphorical knees. He had wrestled DARPANET from the hands of the United States military with nothing but a computer and 300-baud dial-up modem, both of which he had built himself. He had built a machine that watched over billions of people, ever scanning for threats and dangers to society. Yet considered himself an ethical hacker. A gray-hat, so to speak. The things he did were quite illegal, but they were for a good cause. They saved lives. They bettered the world.

But Root thought she was working for a good cause as well, he thought. He shuddered, did his best to put the thought out of his head.

Elizabeth Ruben tugged at his conscience. Gaining access to her network had been a necessary act, he told himself. It might save her life, or save someone else's life. Then he thought of her, sitting in her bedroom, surrounded by the disassembled remnants of her network, forced to wipe clean her own computers, one at a time, to regain a feeble feeling of security. She'd probably replace the router too. Possibly the network switch. She would likely open up every computer and examine it with a critical eye, looking for any nefarious hardware that might have been added, such as a hardware keylogger. If she was as paranoid as Finch, she would examine her keyboard as well and replace the mouse. Then scan for cameras.

Harold Finch hadn't thought about the effects of his exploits for some time, because until now, no one had detected them. The more he thought about Elizabeth Ruben, the more he realized that he had acted in haste, and the more he wished there was something he could've done to help repair the damage he had caused.

Saving her life would be a decent start, he thought.

Sighing, he opened the laptop again, borrowed a neighbor's open wireless network (for a good cause, he told himself), connected to HQ through an encrypted tunnel, and reviewed the files on Elizabeth Ruben's coworkers, searching for some thread, some scrap of information that would reveal who was the threat—or the target.

He was still working on it when John Reese returned an hour later.

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