A/N: Many thanks again to everyone who's been following this story. I apologize if it seems a bit slow so far - lots of groundwork to be laid before we get to the really meaty stuff, which is coming up starting in Chapter 5. Stay with me, folks!

Spoilers: Nothing major in this chapter.

Disclaimer: All NCIS characters are owned by CBS, and no copyright infringement is intended.

Sunday, May 30, 2010 7:15 p.m.

The Tordella Supercomputer Building was like one giant candy story to Timothy McGee. It reminded him of his school trip to the Hershey chocolate factory in Grade 3 - everywhere he looked, there was something drawing his attention, and it took every ounce of willpower he had to follow in step with Commander Schumacher's quick pace as he tried to take it all in.

They ended up in what would normally be described as a "hive". In the centre, computer equipment extending from floor to ceiling. Surrounding this, dozens of technical specialists would usually be manning various stations around the perimeter; but with the lockdown in effect, the room was eerily quiet, with only a low hum coming from the bowels of the machinery. McGee slid into position at one of the surrounding workstations, hooking up his laptop and connecting the webcam feed to Abby's lab at NCIS Headquarters.

"Hi McGee! Are you in heaven?" Abby chirped.

"Pretty much, Abs. It's amazing! I thought the mainframe systems at MIT were impressive, but I've never even imagined a setup like - "

"Uh, Agent McGee, we should be tracing that signal. Time is of the essence," Schumacher interrupted gently. He well remembered his own fascination with the NSA computer warehouse when he'd first arrived some 15 years earlier, and today's installation was light-years ahead of what they'd had back then. But his neck was on the line, and he needed to keep these agents on-task.

"Of course. My apologies. May I introduce Abby Sciuto, our forensic specialist?" McGee pointed to the auxiliary screen. "Abby, this is Lieutenant Commander Schumacher. He's in charge of the communications computer systems here at NSA." McGee was typing furiously as he spoke, starting up his sniffer software that he hoped would be able to locate the source of the illicit communique. He input the IP address that Central Security Service had identified. "Abby, you picking this up?"

"Got it." The goth studied the plasma in the lab as the data flashed across the screen. She grabbed her Caf-Pow and sucked the straw deeply, for an extra dose of energy. They let the software run for about an hour, making small-talk all the while. Abby was multi-tasking as usual, simultaneously reviewing the video stream from the various security cameras in the SIGINT division that Gibbs had ordered transmitted to her. She shifted her attention back to the sniffer, and sighed in frustration. "Something's hinky, Tim. Every time it gets close, it diverts to another node. It's like someone's deliberately blocking us."

Schumacher had been studying the screen intently, fascinated by the program McGee was running (a custom job he'd come up with while he was stationed in Norfolk, which Abby had once declared 'absolutely brilliant', and which had come in handy more than a few times). "How exactly does this software monitor the trace?" he inquired. McGee explained the algorithm to the Commander, and as he processed the information, he began to shake his head. "You're not going to have any luck with this, I'm afraid. Our systems use a random number generator and fluid IP addressing - any one workstation will only maintain its current address for about 20 seconds before the next one is assigned."

"That's wicked!" Abby exclaimed, half-smiling, half-grimacing. "Do you know what that means?" She didn't stop to wait for his response, instead continuing excitedly. "That means, unless we can crack the algorithm used by the random number generator itself, and backtrack the timestamp to the millisecond the transmission was sent, there's no way to trace it." She yanked on her braids in frustration. "Gibbs is gonna be one unhappy boss-man," she pouted.

"No, wait Abs. I have an idea. I think the Cyber Crime Unit might have the equipment we'd need to figure this out." McGee turned to Schumacher. "We'll need to link them up directly with your systems."

McGee didn't need Schumacher's permission to proceed, nor was he seeking it, but nevertheless the Commander acquiesced. "Go ahead. I need to know who's responsible for this mess. We're dead in the water until we identify the mole; there's no way I can re-open the com lines under these circumstances."

Abby was already on the line with Cyber Crimes, and they quickly established the linkup. Realizing there was nothing more he could do for the next while, McGee decided to seek out some much-needed sustenance, and to check on Tony and Ziva's progress with the interrogations. If they could narrow down the list of possible suspects, they could cross-reference them against whatever trace Cyber Crimes was able to come up with. Schumacher escorted him back to the main building, where he came across a very flustered pizza delivery guy at the main security desk.

"It's for someone named Gibbs."

"Got anything more than that? We got 7 people here named Gibbs. We got Phillip, Julia, Nathan, Steve..." The burly security guard was clearly enjoying this.

"Jethro. Jethro Gibbs."

"Nope. Don't got a Jethro. Got an Andrea, a Mike, and a Stewart, though."

"I'll take it to him" McGee stepped forward, flashing his NCIS badge at the bemused security guard. Schumacher nodded approval, and the pizza guy let out a sigh of relief.

"Thank God. Took me 45 minutes just to find this frickin' place. That'll be $37.50."

McGee's eyes widened in shock. "You're joking, right?"

"Nope. Includes a surcharge for delivery outside our normal area."

The junior agent was almost certain this guy was padding the bill, but he was starving, and didn't have any way of proving it one way or the other, so he forked over two twenties, muttering "Keep the change," grabbed the two large boxes, and high-tailed it upstairs to their makeshift command centre, led by the Commander. He couldn't resist sneaking a piece out of the top box as they rode up in the elevator. It was cold. Not even lukewarm. 40 bucks for a couple of slabs of cold dough with weird toppings.

9:07 p.m.

"You did not answer my question." Ziva's eyes narrowed as she regarded their latest interviewee from across the table with derision. Jake Halden smirked, leaning back in his chair and letting his eyes settle on the centre of her chest.

"You didn't ask nicely. Where I'm from, a lady doesn't talk to a man like that."

Tony, lying on the couch with his feet up on the arm, resisted the urge to get up and threaten to clock this jerk, Ziva having cast him a sideways glance that said, I can handle this. And well he knew she could.

"You are under orders to answer any questions we ask, Petty Officer." She let the title drip off her lips mockingly. "It would be in your best interest to do so. Or perhaps you would enjoy a formal reprimand from your superior officer for failure to cooperate with Law Enforcement?" He sat up in the chair and wrinkled his nose at her. "Now, shall we begin again? Where were you between 16:30 and 17:00 hours?"

"At my desk. I'm working on an NK cypher - kind of a specialty of mine, you can ask around. But I may have gone to the head at some point in there. Can't really recall. It's not the kind of think you keep track of, know what I mean?" He rambled casually, in his best matter-of-fact tone of voice. "By the way, can't help noticing, you have a gorgeous body," he crooned. "Under different circumstances, I'd love to - OOOFF!"

The tip of Ziva's steel-toed boot made perfect contact with Halden's crotch. "Thank you. We will be sure to verify your statement against the security footage. That will be all for now, Petty Officer." She smiled sweetly and nodded to Tony, who dutifully stood up and opened the door. Halden limped out sheepishly, deliberately avoiding eye-contact with DiNozzo.

Tony cocked his head towards Halden as he ducked past. "I coulda warned ya. But I kinda like the element of surprise," he clucked. The senior field agent grinned from ear to ear as he watched the disgruntled man skulk back to his station. Halden's co-workers were transfixed as he passed by, and Tony noted a particularly devilish smile on the face of Petty Officer Penachetti.

With the room vacated and the door shut once more, Ziva and Tony compared notes. "Chauvinistic pig. But not our mole," Ziva summarized, as she typed her notes in the laptop.

"And on what exactly do you base that conclusion?"

"Too busy trying to make a goal."

A puzzled pause, then a glint of comprehension on Tony's face. "It's score, Ziva. Trying to score."

"Whatever." She shook her head in frustration. She didn't make nearly as many slip-ups like that these days, but, like Tony, she felt hungry and irritable, and it was all she could do to maintain her concentration on the task at hand. Worrying about using the correct idiom in the situation was the last thing on her mind. "If he had something to hide, he would have been much better behaved."

Tony felt too exhausted and headachy to argue, although something didn't sit right with him about Halden. He just couldn't pinpoint what it was. His stomach growled again. "Where the hell is that pizza?" The door swung open as if on cue, and in marched McGee, carrying the two boxes with their long-awaited dinner. Tony dived at the top box like a piranha, pulling out two pieces at once and stuffing the corner of the first one in his mouth, before grimacing ruefully. "Cold. What did I tell ya?"

"Yes, thank you, I would like a piece."

He swallowed and stopped dead in his tracks, not knowing what to do with Ziva's calm yet slighted reaction. "Sorry. Here." He shoved the bottom box towards her across the table, smiling sheepishly.

She just rolled her eyes and grabbed the box, inspecting the contents and wrinkling her nose with disdain. "What do you suppose the fat content of this is?" she inquired, inspecting her slice of pepperoni-mushroom-double-cheese from various angles.

"We could google it." McGee nodded towards the laptop.

"I think it was a rhetorical question, McGee." The undercurrent in Tony's voice seethed, for the love of God, McGee, don't provoke her. He still had about 10 more interviews to get through with the Israeli spitfire before this evening was out, and he needed to keep her in some semblance of a cooperative mood.

Gibbs marched in and picked the pizza slice right out of Ziva's hands, biting into it without a word. "Progress?"

She didn't even flinch, Tony noted admiringly. "We are not in agreement about our last subject," she commented.

Gibbs responded, "Abby's finished going through the surveillance footage. Didn't find anything. Nobody left that room within our time window, except to use the washroom..." Ziva gave Tony an I told you so glance. "...which means whoever sent that message did it from their workstation."

"Either that, or they programmed it earlier, to be transmitted at a set time...," McGee chimed in, between bites. All eyes turned to Tim disapprovingly. The last thing they needed was an alternative theory at this point. He glanced furtively from Ziva, to Tony, to Gibbs, then back again. "...or not."

"CSS already ruled that out," Gibbs shot back. His cell mercifully rang to break the tension, and recognizing the number on the display, he stepped aside to take the call. "That was Admiral Penachetti. They've detected three IDF vessels on an intercept course with the Flotilla. They left Haifa about 10 minutes ago. We're running out of time, people."

Tony grabbed the pizza boxes and tossed them onto the coffee table beyond the sofa - but not before Gibbs had grabbed another slice of Grand Hawaiian. McGee and Gibbs quickly vacated the room, to where Schumacher had been waiting patiently and making small talk with the SIGINT technicians to try to relax them a bit. They were highly strung individuals at the best of times, and all this drama wasn't helping. Gibbs motioned for the next interviewee to enter. By the time he got to the door, Tony and Ziva were back in position, steely expressions on their faces, with renewed energy and determination to figure out this puzzle.

9:23 p.m.

As Schumacher led the way back to the Tordella Building, McGee briefed Gibbs concerning the status of the sniffer trace, explaining why he'd handed it over to the Cyber Crime Unit. Unfortunately this was not the type of work that could be done properly under intense time pressure, and they were refusing to be bullied into speeding things up, regardless of the invective being hurled at them by Gibbs. It could potentially take several days to complete the trace. At this news, Gibbs slammed his coffee down on a nearby workstation, and glanced at his watch once more. He couldn't just sit here doing nothing! He flipped open his phone and called the Admiral back.

"Admiral, this is Gibbs. Can you give me an update on the Tenth Fleet's progress in decrypting that message?"

"As a matter of fact, I can, Agent Gibbs. Just got the report a moment ago." There was a pause as Penachetti slid on his reading glasses. "Beware ships leaving Cyprus 15:00 EST. Mavi Marmara is Trojan Horse. Activists support Hamas. Armed and dangerous. Destination Gaza. End Transmission." It was just as they'd feared. Someone wanted the Israeli government to believe that this was not just a peaceful aid mission. But the fact was, no-one, not even SECNAV, knew the truth about the protesters' intentions, or whether or not they really were carrying weapons on board. So, where was the messenger getting this information? And was it accurate, or just a red herring meant to stir the IDF into hasty action that would cause untold embarrassment? Penachetti continued, "The Secretary of Defence has been on the horn with the Israeli Ambassador for over half an hour, trying to get assurances they won't engage them until we figure this out. But we're not holding out much hope of success at this point. Those naval ships they sent out to intercept the Flotilla were staffed with heavily armed IDF commandos. They've got helicopters on board. Not much doubt they're readying themselves for a fight...is your team making any headway?"

Gibbs winced at the query. "We've narrowed the list of suspects, but whoever did this had incredibly sophisticated computer skills. We've got our Cyber Crimes Unit working on it right now. The mole can only hide for so long - we'll find the leak, Admiral." He slammed his cell phone shut before Penachetti could broach the logical next question: but will you find it in time to stop an international incident?

Monday, May 31, 2010 12:47 a.m.

Tony yawned as the last of the SIGINT personnel to be questioned shuffled out of the staff lounge. His head slumped down onto the table and he let out an exhausted moan. He'd now been awake for just over 24 hours, and his internal clock was all screwed up. His 39-year-old body couldn't handle these all-nighters anymore, and he doubted he was of much use to the investigation in this state. Ziva methodically shut down the laptop and began packing up the equipment, working around the now dozing senior field agent. Being ten years younger had its advantages; she barely felt the effects of sleep deprivation. A tiny piece of her felt sorry for Tony - but just a tiny piece. She head-slapped him, slightly more gently than Gibbs would have, out of pity, but it was enough. He jumped to attention. "I'm awake, Boss!" He glanced around furtively, and seeing only Ziva, a cheeky grin on her face and a twinkle in her eye, he frowned disapprovingly.

"Help me clean up in here."

"Oh, so I get kitchen duty, is that it?" he moaned, glancing around at the array of empty water bottles, napkins and pizza crumbs strewn about the lounge. "Did you send our short-list to Cyber Crimes?"

Ziva nodded. "They will cross-reference the data once they have narrowed down the source of the signal. Apparently they cannot do it the other way around. Something to do with random numbers..." she trailed off, having ventured into unfamiliar territory. "I speak nine languages, but unfortunately Geek is not one of them."

Tony snorted. His partner's jokes were improving, he thought to himself admiringly. "We'll have to get McNerd to explain it to us." DiNozzo dragged himself around the room, gathering up the varied detritus from their five-hour interrogation odyssey and jamming it all into a smallish garbage can at the end of the counter in the kitchenette. "You want any more of this?" he inquired, pointing derisively at the leavings of the Grand Hawaiian pizza.

"Those bottles can be recycled," she observed, deliberately ignoring his question.

He shrugged, tossing the leftover pizza slices into the garbage and abandoning the boxes on the counter. Gibbs stuck his head in the doorway just then. "IDF has made contact with the Flotilla. They're threatening to engage them if they enter the blockaded area."

Ziva's expression paled. "Can our government not contact the Flotilla directly and urge them to hold back?"

"Don't you think we've tried that, Zivers? They've refused to alter course or to stand down. They're obviously hoping for a confrontation." He sank down onto the arm of the sofa and rubbed his eyes. "I think we're done here. Nothing much more we can do until Cyber Crimes does their thing." He glanced up at his two exhausted agents. Tony was propped up against the wall, with his head back, fighting the sleep that wanted desperately to overcome him. "That was good work tonight, both of you," Gibbs smiled affectionately. The compliment made Tony straighten up and take notice. "C'mon, let's get out of here so you guys can get some shut-eye."

2:23 a.m.

DiNozzo collapsed into bed, after listening to an incredibly agitated, 5-minute rant left on his answering machine from his best friend. Pete was mad. He didn't remember ever hearing quite such an infuriated tone in his voice in all the years they'd known each other. Louisa must have called him to fill him in on the details of her interview. He resolved to deal with Pete later, when he'd cooled off a bit, secretly glad he hadn't been home in time to take the call.

He tossed and turned. Despite being dog-tired, he just couldn't get to sleep, for worrying. Not about Pete, but about his sister. Had he been too hard on her? Had he really let himself get carried away with the control thing? Had he panicked her unnecessarily? He ran through the interview in his mind.

She'd come out swinging, on the defensive right away. She'd invoked her father's name, as if she needed that leverage to help her. And, worst of all, she'd lied. They knew, from their study of her profile, that she had both the skill set and the authorization to send outgoing encoded transmissions. Why would she deny this, unless she was hiding something?

The true misery of his predicament hit him then - what would he do if she did turn out to be the mole? Would his friendship with Pete be able to withstand the strain? Would that be the end of Thursday evening pick-up basketball games and Stanley Cup playoff parties in front of the big-screen TV in the Penachetti basement? Would Pete blame him for exposing her?

It certainly didn't look good for Louisa, but then there was that gut instinct again - he just didn't sense any malice in her. And what about motive? What possible reason could she have to send a message that would instigate a potentially lethal confrontation in international waters?

Tony's head was pounding, and by 3:00 a.m. he realized he would not find any answers this way. He rolled over onto his stomach, hugged his pillow and fell into a fitful sleep.