"As long as we keep this in a pH-neutral saline environment, it will keep transmitting," Wolf said in his quiet way. "It seems to be drawing energy from the ions in the solution."

"It was using my body's natural salinity to power itself?"

"I believe so. It has no independent power source. It's smaller than anything I've seen before, and it makes sense to have it utilize the chemistry of its anticipated environment."

"That's diabolical."

She was appalled by the idea that such a thing was even possible. This technology was way ahead of anything she'd seen before, and she had prided herself on being at the cutting edge of biotech.

"Your friend Rodriguez had access to some amazing stuff," Wolf commented in his calm way.

"He's not my friend. Never was." She wanted to make that perfectly clear.

Wolf bowed his head slightly. "My apologies. I only meant that you'd worked with the man before." He turned back to his instruments. "Other than the power source, this thing is similar to an RFID tag used in many commercial applications."

"What does that stand for?" she asked.

"Radio frequency identification. It's used in a lot of different ways. One way is to label items so when they're brought past a scanner that's tuned to the right frequency, the item is automatically identified and charged to a particular account."

The phone rang and Wolf went to answer it while Sandra stole another glance at the tiny chip under high-powered magnification. It really was the most amazing thing. Scary as hell, too. She'd been easy pickings for their enemies. All Rodriguez had to do was pinpoint her location using this hidden chip and send his goons after her. The bastard.

"We've been summoned." She jumped at the soft words. Wolf had snuck up on her. The man moved as silently as his namesake.

"Where to?"

"Commander Sykes wants to talk to us in the conference room. Come on, I'll show you where it is."

He switched off a few lights and motioned for her to precede him out the door.

The conference room was larger than Sandra had expected. It looked like most, if not all, of the combat team was already there, along with the members of the cleanup crew. Mariana waved hello. She was seated next to Simon. The two looked good together. Comfortable. Like they belonged together and didn't really care who knew it. Sandra envied her colleague just the tiniest bit.

Then Matt caught Sandra's eye and motioned her over. He'd saved her a seat next to him. That was as close to a public statement as anything among this group. He'd just tipped them all off that something was special about their relationship without having to say a word. A warm feeling spread through her body. Maybe she didn't need to be so envious of Mariana and Simon's relationship after all. Sandra took the seat next to Matt, and he called the meeting to order without further ado.

"First off, I want you all to know that I've sent two technicians from the cleanup team to Tennessee. They're going to assist John and Donna, so we're going to be a little short staffed until they can get things under control down there. We have enough of our own problems or I'd send more help to them. As it is, we're stretched too thin. As of today, we're going to get more centralized. We're all moving in to this building. It's the most secure building we have fully at our disposal, and I believe there's truth to the old adage that there's safety in numbers. So I want everyone who's not already bunking here to pack up your gear today and move to one of the empty rooms in the barracks area on the second floor. And we're going to buddy up. Nobody leaves this building alone-day or night. Our adversaries have proven they can get on and off this base with impunity. From here on out, nobody goes anywhere alone."

A few people looked around curiously, but most took the news in stride. These soldiers were used to orders changing on the fly.

"As you all know, we've had a major increase in zombie activity the past couple of nights. Unfortunately, I expect that trend to continue. A change of tactics is in order. I'd like to start taking the fight to the enemy instead of the other way around. We've had a few direct attacks on Dr. McCormick. I don't think they've given up trying to get to her." All eyes were suddenly focused on Sandra, and she did her best not to squirm under their scrutiny.

Matt gave a signal to one of the men near the door and the lights were lowered. A second later, a projector went on and Dr. Rodriguez's face shone against the side wall of the room, which doubled as a screen.

"This is the member of the original science team we now believe is responsible for our problems here at Bragg. Dr. Emilio Rodriguez. He's a biotech expert who apparently has some dangerous friends. The man we captured and lost yesterday is a known associate of his. Allowing the prisoner to escape was a tough break and I blame myself." Matt paused a moment, a pained look on his face. "Lew Kauffman is going to be okay-I got an update right before we began this meeting-but he'll be laid up in the hospital for a while, I'm sorry to say." Hard expressions greeted him at this news. Kauffman was a member of the combat support team and clearly had a lot of good friends in here.

Sandra saw Matt nod at Wolf. He got up and went to the projector. Wolf tapped a few keys, fiddled with something, and a few seconds later a microscopic image of the circuit board they'd dug out of her hip appeared on the screen.

"This is a locator chip that we found implanted under Dr. McCormick's skin." Matt nodded to Sandra, then looked at the tech expert. "Wolf, tell the team what you've discovered, please."

Wolf went into more technical detail than Sandra expected, showing several views of the chip to give the rest of the team an idea of its minuscule size. Scowls shone on many of the faces around the room as he drew his short presentation to a close. He sat down, returning the floor to Matt.

"I believe the prisoner must've had one of these under his skin, too. That had to be how they knew exactly where to find him. Sandra was tagged without her knowledge, and I believe Rodriguez may have tagged other members of the original science team in the same way. Mission objective has expanded to include the takedown of Dr. Rodriguez and if at all possible, the seizing of his technology, files, and equipment. If we can learn the secrets of his tracking system, and if he's really able to pinpoint the location of the other scientists, we could do the same. First we need to find Rodriguez's base of operations. Wolf's heading up that task. Once we know the location of his headquarters, the combat team will be working on a plan to secure the area."

Sandra read grim determination on many of the faces around her. These guys were goal oriented in a major way, and Matt had just handed them a challenge.

The meeting broke up shortly thereafter, and Matt motioned for her to stay behind while the others filed out of the big room. Mari stayed, too, though Simon took off with the other soldiers.

"Mariana's got an idea I'd like you to examine," Matt said once the three of them were alone.

"I've been working with the formula of your serum and Sarah Petit's blood test results. I believe I've isolated the particular protein sequences in her blood that allowed for her spontaneous immunity." Sandra was intrigued by Mari's words. "I then compared the sequences to those in her brother's blood. Having siblings on the team opened a unique avenue for study considering one had already been proven immune and the other is still in his natural state."

Sandra recognized the scientific importance of testing two people who had such similar genetic makeup. The only way the experiment could be better is if they'd been given identical twins to work with, but that was asking too much. Siblings was what they'd gotten. Siblings would have to do.

"That was a really good idea." Sandra congratulated the other doctor.

It was a smart move from a scientific standpoint. One that Sandra would have thought of if she hadn't been so distracted by all that had gone on in the past few days. Good thing Mariana was on the ball. Sandra's usual focus had been blurred lately, her mind in a state of chaos.

"Thanks. What I've discovered-I believe-is a way to make John Petit immune."

"Are you kidding?" Sandra was shocked by the idea.

"He has almost all the same protein sequences as his sister, except for two that could potentially pose a problem if he's exposed to the contagion. Based on my lab studies, he has a less than fifty percent chance of being spontaneously immune."

"Those are not good odds for him." Sandra frowned. "But you've isolated the problematic proteins?"

"Yes." Mari looked triumphant. "Which is why I think we could coax his body into a much higher probability of achieving immunity."

"Before exposure? The serum I developed is designed to negate exposure after the fact. Changing someone's genetic makeup before they're exposed seems too risky, not to mention the ethical problems. I mean, we don't know the long-term effects."

"I wouldn't even consider this under normal circumstances, but we're in a bind and I don't want John dying if we have a way to prevent it." Matt's expression was troubled as he spoke for the first time during this exchange. "John and Donna are in a volatile situation, and Donna isn't really up to the task, even though she's immune. John needs to be able to fight without risking his own life every time he faces one of those creatures. If he were to become an infected, I hate to think what he could do. From the beginning we've noticed that some of the person's skill and ability survives their death. John is an elite warrior. We've had a hell of a time tracking soldiers who've been turned. John would be a nightmare to neutralize, and Donna just doesn't have the skills. Nor can I spare anyone from here right now." Matt ran a frustrated hand through his hair. "I think we need to give him the option." He blew out a sigh. "I want you to look at Mariana's work, Sandra. Put your heads together and be as sure as you can that this will work before we go any further."

Sandra was uncomfortable with the idea of testing a theory on a live subject, even if John turned out to be willing. Still, it would advance their research considerably, no matter the outcome. Sooner or later, they'd have to put their theories to the test. If John was willing, Sandra would put all her energy toward being certain the test was as safe as it was possible to make it, under the circumstances.

"Okay," she agreed cautiously. "I'll take a look. Where are we working today?"

"I have some guys moving your lab over here as we speak," Matt replied. "There's a lot of space in this old building. It's not quite as comfortable as where you were, but it's a lot more secure. Now that we know the base isn't safe, I'm kicking myself for not having us all here in the first place. Come on, I'll show you where we're setting you up." Matt headed for the door, and Sarah and Mariana followed him out and down the corridor.

A few flights of stairs and several more hallways later, they arrived at a big space that was fast being converted into a makeshift laboratory. The guys had already made good progress setting up tables, and even as they watched two more groups arrived with equipment from Sandra's lab.

It took an hour or two to get everything set up, but Mariana and Sandra were able to start working almost right away. The guys worked around them, putting everything else in place while the two women put their heads together in one corner of the large room.

It didn't take long for Sandra to verify Mariana's work. She may have come to the team as a general practitioner, but Mariana definitely had a good head for research. They worked well together, and before Sandra knew it more than two hours had passed. The fourth time Sandra yawned, Mariana closed the reference book she'd been holding with a bang that startled Sandra into nearly jumping off her stool.

Mariana laughed. The twinkle in her eye was hard to resist and Sandra chuckled, too.

"Time to get some much needed sleep." Mariana began putting things away. "Doctor's orders."

"Don't worry. I won't argue with the prescription. I'm beat." Sandra got to her feet slowly, suddenly remembering something vital. "Only...I don't know where I'm supposed to sleep now."

Mariana's attention shifted over Sandra's shoulder. "I don't think that'll be a problem much longer."

Sandra turned to find Matt coming into the room behind her. He looked as tired as she felt, but his fatigue didn't slow his determined stride. She had to hand it to him. The man had outstanding stamina-as she was coming to know firsthand. She felt her cheeks heat with a blush as the slightly racy thought crossed her mind.

"Looks like the lab is coming along. Anything else you need brought in here?" Matt asked both ladies.

Mariana surveyed the room, her hands on her hips. "No, it looks like they've got just about everything we need for now, thanks."

"So what's the verdict on your research?" He looked at Sandra expectantly.

"My conclusions are the same as Mariana's. Her reasoning is sound and the treatment should work to make John immune to the contagion."

A look of grim satisfaction crossed Matt's features as he nodded. "How soon can you be ready to try it?" This time his question was directed squarely at Mariana.

"The reagents are already prepared. We can do it any time."

"Good." Matt looked at Mariana directly. "I'd like you to leave at first light to rendezvous with John and Donna. I've already talked to John about this in some detail, and he wants to proceed. There will be a small plane waiting to take you to Knoxville and back."

Matt didn't bother looking at Sandra. He knew she'd be concerned by his decision to proceed with testing their scientific theories on John. In a way, it was reassuring that she was so concerned about the idea. It told him she had a heart-unlike the other members of the original science team. Most of those heartless bastards didn't care who they injured or killed in pursuit of their goal.

The way Matt understood it, Mariana would give John a series of injections over a few hours. They'd know within a short amount of time whether the plan worked as intended or not. Worst case, John could die, though Mari had said she thought the odds of that were slim. John might also respond badly to the injections, in which case, he could become unfit for duty. Again, the odds of that happening were low, Mariana had assured him. Matt thought it was worth taking the chance to proceed because if it worked as they thought it would, John would survive the session immune and able to fight the zombies without fear of infection.

Right now, Matt needed all the skilled immune fighters he could get. John had the skills; all that was missing was the immunity. It was Matt's hope that Mariana would take care of that on her little excursion to Knoxville, and they could all get on with their assigned missions.

Matt spotted Simon lurking near the door and motioned him inside.

"Almost done here?" Simon asked with a smile for his fiancee.

"We were just going to call it a day," Mari assured him. "The commander just told me he's sending me to Knoxville to see John and Donna."

Simon's eyebrows shot up and he sent a questioning look in Matt's direction.

"It's only for a few hours. Mari can fill you in on the particulars."

With those few simple words, Matt had given clearance for Mariana to discuss her latest work with her fiance. He figured she probably already shared a good deal of her work on the project with him, since he was participating in the study rather closely.

For a while they'd been the only two working on the project at all. They'd dated many years ago but broke up over Simon's career. The zombie problem had reunited them after Simon was exposed and became immune. He'd been the first immune soldier. He'd been the one sent in to eradicate the original problem. The only one. He'd done a hell of a job against awful odds, and then he'd tried to fade into the shadows after completing the mission and settle down with the woman he never should have lost in the first place.

He and Mariana had gotten a second chance, and Matt knew if the contagion hadn't resurfaced they'd be living on a farm somewhere by now, happily married and starting their family in peace. As it was, Mari was pregnant and Simon had been drafted to continue the dangerous work of fighting zombies. Only now he was part of a bigger team and he wasn't the only immune man who could combat the creatures.

While their peace had lasted, Mariana had tried to figure out more about how Simon's systems had been affected by the contagion. She'd been researching it on her own, with Simon's cooperation. He'd been her willing guinea pig from the start.

There were few secrets on Mari's side of that relationship. On Simon's side, Matt wasn't so sure. He'd worked with Simon for many years in special operations. They both had very high security clearances and knowledge of things that were meant to be kept top secret. There was a lot about his work that Matt had never been able to discuss with anyone other than his immediate teammates. The same had to be true for Simon, yet he'd managed to form a committed, healthy relationship with Mariana. That was something to think about.

For years, Matt had thought he'd never be able to commit to a woman because of the nature of his job. Then Sandra had walked into his life-and right into the middle of his mission. For the first time, he could share a mission with a woman he had feelings for. It was a novel experience that still made him feel a little strange.

Somehow, Simon and Mari were making it work. Maybe there was hope for Matt and Sandra, too. Only time would tell.

"If that's all, sir..." Simon looked at him questioningly, and Matt realized he'd been silent too long, keeping them all waiting.

"That's all I've got. You should probably both get some rest."

"Aye, aye, Commander. That's just what I was thinking." Simon held out his arm for Mari to take and with not much further ado, he escorted his fiancee from the lab, leaving Sandra alone with Matt.

"You ready for some downtime?" he asked quietly. Matt had a mysterious expression on his face that Sandra could almost interpret as...a sort of caring concern. Whatever it was, it touched her. When he stretched out his hand, she took it without hesitation and allowed him to lead her from the room.

"Where am I bunking?" she asked on their way out the door.

"With me."

She shouldn't have been surprised by his calmly resolute tone.

"Won't that raise eyebrows?"

"Probably." He let her precede him through a doorway that led to one of the many staircases in the old building. "But I don't really care. You've been in harm's way more than I like, Sandra. I'll be damned if I let you out of my sight any more than I have to."

That sounded a little more serious than she'd expected. She knew she was having trouble separating her heart from her mind where Matt was concerned. He'd attracted her from the very beginning. Everything she'd learned of him since had only increased her crush on him. She admitted in the darkness of her mind that she was already half in love with the man. It wouldn't take much for her to tumble head over heels, and that would spell disaster.

She was holding out on him. That last secret-her secret shame-would destroy any chances for them. She knew it. She understood the danger of getting more involved with him. This could only lead to heartache for her if and when he found out the truth.

But she was powerless to fight it. She wanted whatever time she could have with him. More than her next breath.

He led her to a narrow corridor with lots of doors. He opened the last door at the end of the hall, and she wasn't surprised to discover it was a bedroom. Old fashioned and painted a rather depressing green color, this section of the building must have been used as a barracks at one time. She'd bet the other members of the team were happily snoring behind those other doors she'd passed on the way to this one.

"It's not a palace, but it'll do." Matt stepped into the room behind her and shut the door.

The bed was a double. Surprising in a barracks setting, but since the room was at the end of the hall, more than likely it had been designed for the commanding officer of the rest of those quartered here. She knew RHIP meant rank has its privileges and often those in charge got a little more room to maneuver than those under them. So the head man got a bigger bed, which suited her fine. If Matt was going to insist on bunking with her, she didn't want either one of them to wind up sleeping on the floor.

Matt was already shrugging out of his shirt, moving around the room, letting his fatigue show. The man had to be beat. As she was. The bed looked too inviting. This was no time to quibble over sleeping arrangements or what the rest of the team might think. Let them think whatever they wanted. Sandra was too tired to worry about it now.

She kicked off her shoes, removed her outer layers, and unhooked her bra under her T-shirt. That would have to be enough. She was too tired to do much more. She pointed her feet toward the bed and collapsed on it, her eyes closing almost immediately.

A soft male chuckle behind her was the only warning she got before a warm body settled onto the mattress beside her. Matt's strong hands lifted her, moving her around on the bed to his satisfaction.

"You can't be comfortable like that," he said.

"Like what?" she mumbled, her face smushed in the pillow.

"In all those clothes."

"Too tired to change into my nightie," she complained.

"No problem." Big hands raised the hem of her T-shirt over her head, lifting her as if she weighed nothing at all while he stripped her bare in a matter of seconds. Her pants were pushed down, along with her panties, and within a minute she was naked. "That's better."

Matt's voice purred with satisfaction near her ear as he settled on the bed with her in his arms. Skin to skin. He was naked, too.

Oh, my.

He spooned her, one hand cupping her breast as his body cocooned her in warmth. Her nipple beaded against his palm as her breathing sped.

"Sleep," he ordered, a chuckle clear in his tone.