"Oh my God." Elizabeth's horrified whisper made John Sheppard stand up straight from where he had been leaning against the wall. Rodney and the others in the corridor outside the munitions room paused in their activities.

"Elizabeth?" Sheppard demanded firmly. Gripping his P-90 a little tighter, he waited tensely for a reply.

"Colonel, I suggest all of you head back to the gate room now." Zelenka's voice was subdued and proffessional. "I have map showing affect areas, which now cover about forty percent of city and climbing."

"What about Corosen? The doctors further in the city?" Sheppard knew he was being stubborn. He knew what had caused Elizabeth's involuntary exclamation earlier but if he gave up on Corosen that meant he gave up on the others and he wasn't prepared to do that. Not yet.

"John," Elizabeth started firmly. "I'm sorry, but Lt. Corosen is no longer showing on the life signs detector. It's too late for him. You and those with you won't be helping by getting trapped as well. We are not giving up, John. But you need to bring everyone with you up to the gate room so that they're safe. Maybe with Rodney up in the control room he can help Zelenka with the database and city systems search and we can fix this problem from the ground up."

Rodney began packing up his few bits of equipment along with Kusanagi, who had appeared not long ago and had been assisting him. Carson was staring at the crystals and bits of circuitry they were leaving behind, looking fairly ill. Sgt. Smigs was standing preternaturally still at the end of corridor, where he had stumbled numbly to after hearing about Corosen.

Generally, Sheppard was glad Elizabeth could collect herself at times like these. Her common sense and ability to think in these situations were a few of the reasons he trusted her so much. Much more than any other commanding officer he ever had. Sometimes, however, his instinct to disobey was so strong he wished she were a little less strong willed. A little less conscientious.

A little less right.

"We'll be there in a little over five minutes," John said shortly. He tried to ignore the look of relief in Rodney's eyes. Some people here in this galaxy had gotten to know him very well and sometimes it could be a pain in the ass. He found it frustrating how people closest to him sometimes wondered if he risked too much, if he did it on purpose. He was prepared as all soldiers were to die doing their duty but was in no way looking forward to going out in a blaze of glory. He wanted to die of old age after living a fulfilling life, not when he was still young. Relatively, he thought ruefully.

Coming back to himself he realized he had been staring at the door to the munitions room. McKay had been calling to him from where he and the others had caught up to Sgt. Smigs, ready to head to the gate room. He shook his head and joined them

"Major Lorne, I want you to pick a room with an outside wall and sit tight. If the room shuts down, you use that explosive to blow yourselves a hole and radio yourselves a jumper evac," Sheppard ordered tightly.

"Yes, sir. Understood. Lorne out."

"You okay?" McKay asked as the two of them took up the tail end of their little procession through the halls. He was visibly uncomfortable with trying to comfort his friend but Sheppard gave him some credit for trying. He was glad Teyla had taken a week's leave to the mainland to handle Athosian business and had taken Ronon with her. This way he didn't have to worry about them being separated from him, suffocating to death while he calmly walked to safety.

Sheppard stared straight ahead. "I'll be okay as soon as we fix whatever's wrong with our city," he replied.

McKay nodded thoughtfully. "The thing I just don't get is why this started happening. I mean, we weren't doing anything invasive with the systems. We weren't activating anything new. None of the systems we had running are indicating any problems. I mean, there should be some indication of where it's coming from if not what's caused it."

"Could it be a virus?" Sheppard asked distractedly. McKay can go on and on about hating when people interrupting him when he's speaking about a problem. But he had a tendency to stick to one issue if someone didn't prod him along every once in a while.

"Yes it could be. And I have Michael Bishop, one of our programmer slash coder extraordinaires researching that possibility. If it's a virus, even another one by the Go'auld that could get around the security protocols of Atlantis, then it should be leaving some kind of a trail. But it would also be affecting whatever system it infected to cause these malfunctions, and there is no sign of that."

"Colonel? We've got a problem," Elizabeth said urgently over the radio. Sheppard stopped in the middle of the hallway, everyone else doing the same before turning to look at him.

"Go ahead," Sheppard responded wearily.

"I'm afraid the way you were taking is blocked now up ahead from your location. You need to back track the way you just came, go through section E-4 of the living quarters and go up the back stairwell three flights. It's the long way, but once you get on the right floor, it's nearly all open. Worse comes to worse we can do a jumper rescue through the glass."

"I would hurry. The rate of malfunctions is still climbing. Nearly fifty percent now," Zelenka explained.

"Right, of course. All right people, you heard them. Let's turn around. Sergeant, lead the way." Sheppard lightly pushed McKay into the wall so that the others could pass first, earning him a glare. Grinning cheekily, Sheppard started following behind the group. McKay caught up quickly.

"You know, this would be a lot easier if we had the transporters," McKay griped as he exaggeratedly rubbed his shoulder where it had connected with the wall at minimum force.

Beckett turned his head and slowed a bit to walk just slightly ahead of his two friends. "Aye, I've been meaning to ask you. Is the problems with the transporters related to this?"

Rodney sighed heavily and dropped his arm. "I don't think so. They've gone down several times this month due to the crystals burning out from surges at certain locations. And when one goes down? They all go down. Zelenka's had Yonick and Rewning do an investigation into the problem but those two couldn't find their way out of a maze on the back of a children's cereal box. Zelenka was supposed to look into it by the end of this week because it's not like we have an unlimited supply of those crystals."

They were silent for a moment as they passed the munitions room, lost in their own thoughts

"Although I suppose that could have been the beginning of the problem," Rodney said thoughtfully, as if there hadn't been a full three minutes of silence since anyone last spoke. "And if that's the case then we might never figure this thing out," he continued to himself oblivious to Carson and Sheppard staring at him.

Sheppard let curiosity get to him when McKay didn't continue. "Why would that be worse than the problems being unrelated? Wouldn't that be one more clue to what's wrong?" He looked at Beckett to see if this made as much sense to him as it did in his head. Beckett just shrugged his left shoulder and looked to McKay.

"Yes, if the two clues together gave us a clear picture of what was wrong," Rodney said. He rubbed his shoulder again while staring at Beckett, obviously wanting to complain for sympathy. For his part, Carson just gave him a 'don't start now' look while staring back. Rodney crossed his arms huffily.

"The fewer systems that are affected, the more of a chance that the problem is in one of those systems," he continued irritably, "and just causing a domino reaction That means we're on the right track as we look into those specific systems. The more systems affected, the more likely the chance it's coming from an outside source. Which leaves us with two possibilities."

He raises a handed with his index finger pointed. "One: It's a virus, which means it was introduced into the system by someone who designed it to not be detected easily. Twice as hard to find, trace back to its input point, and fix the damage it's already done. Or two," he raised another finger. "It's some kind of program that had been dormant in the system but is now active. Whether it's faulty, or it's the Ancient's idea of a fun filled day of panic and death, it's going to be hard to find. The database for the control systems of the city is huge. We've looked over maybe five percent of the systems we don't use on a regular basis. To find which one is doing this and how to turn it off would take a large amount of time we don't have."

Sheppard and Beckett looked at each other grimly, finally getting how close they are were to being locked out of their home for a good long time. Behind them a door to one of the public areas they had just passed had closed on its own without warning, making McKay jump and Sheppard bring his gun up. Everyone in the group looked at each other, and began to walk much faster. Soon, they were just a turn away from the stairwell and everyone was breathing a little easier.

"Colonel, the stairwell has locked down! You are shut out of the gate room!" Elizabeth said, sounding alarmed through the radio.

"You have got to be kidding me!" Mckay said, breaking away from the group to hurry down the hall. Sheppard raced after him, finally catching up at the door to the stairwell. McKay removed the access cover of the control unit to reveal unlit crystals, inactive and powerless in their slots.

"Oh, bloody hell," said Carson, coming up behind them with the others following. Sheppard leaned back against the wall near the open access panel, and closed his eyes for a second, breathing deeply. He mentally ran over the city floor plans in his head and came up with no other way to the gate room. Now his only option was to get these people to an open space where a jumper could pick them up later.

"Elizabeth, Radek, where is the closest open area near our location? The place is closing in around us." Sheppard asked as he studied the two hallways at right angles to each other. One lead deeper into the city and away from the possibility of balconies, but closer to the actual East Pier open to the outside. The other, the dead end they just came from, might have balconies off some of the still open doors along the way. The farthest he had come down this hallway was the munitions room. It was all labs down here.

"The map up here doesn't show if there are any balconies, John." Elizabeth explained through the radio. "I can trace you to one of the patios off the East Pier, but I'm afraid you have to go deeper into the city then back out to the left. It'll take some time."

Sheppard grimaced, the news not helping the feeling of being closed in. He was never afraid of small spaces but was now feeling a bit like Han Solo in Star Wars when he was about to get smashed by the walls of the trash compactor with nothing to do about it. He had a crazy flash of Rodney and Zelenka playing R2-D2 and C-3PO and trying to stop it from happening, but dismissed the thought before he decided to dwell on which one was which.

"The lounge across from storage." A female voice said suddenly, interrupting his thoughts. Sheppard was a bit confused about who it was, until Beckett turned around and he could see a surprised looking Kusanagi staring at him.

"I'm sorry?" McKay asked. He had been ranting about something and John had apparently tuned him out, used to listening for a certain tone of voice to know when he was actually saying something important. Kusanagi turned pink, and looked down at her shoes briefly before turning her eyes to McKay.

"I'm sorry to interrupt, Dr. McKay. But if we need to go deeper into the city to find safety, there is a small patio right above the water across from storage E-7. It is the only one I know of in this area." She motioned her hand toward the hallway that led deeper into the city. "It is this way, about ten minutes down, just before the turn I believe Dr. Weir wishes us to take." Her accented voice was soft, but certain.

John had always liked her, and not just for the entertainment value of the awkwardness her crush on McKay sometimes caused in the man. She always seemed to pull through.

"Sounds good to me," John said relieved, and motioned everyone to go before him before starting down the hallway himself. "I have a feeling it'll be a good thing she knew that," he said as an aside to McKay. The other man just nodded, having pulled out his data pad when they stopped and was tinkering with it. Sheppard shrugged his shoulders and continued walking, not noticing a few seconds later when McKay stopped until he called for him.

"What's wrong?" Sheppard asked, beginning to walk back towards his friend. McKay just waved his hand and caught up with him.

"Zelenka. I want you to check out that security folder we found. With all those protocols we either couldn't understand or thought were completely ludicrous? Maybe we tripped something without even realizing it." McKay had that calm air that he only wore when he was figuring something out, so Sheppard figured he could be excused if he was getting a little excited. Maybe not so doomed after all.

"Yes, I remember," the other scientist answered. "I'll look into it, see if anything was activated."

McKay nodded and continued walking while poking at his data pad, oblivious to the anxious stares of both Sheppard and Beckett. "Well?" Sheppard asked a little heatedly when it was apparent McKay wasn't going to explain.

"Hmm? Oh, yes. Sorry. Well it's just a thought, but I was just thinking about how the city is removing all the oxygen out of the rooms. It seemed a little funny to me to be just a glitch, but weirder things have happened to us. Hell, weirder things have happened to us this week," McKay snorted. Carson impatiently made, 'yes, yes, move on' gestures with his hands and McKay scowled but continued.

"I got an e-mail from Kavanagh here saying one of his chemistry idiots must have accidentally turned on some kind of gas emitting system. It's in their area, but in a lab no one uses. They investigated the power drain and found that some kind of machine had started mixing pre-stored chemicals together forming what proved to be a pretty powerful knockout gas. Some of the gas had been released through some kind of venting system before they were able to shut it down. They had to remove the power source to get it to stop."

McKay stopped there, looking back and forth between Beckett and Sheppard. Sheppard looked at Beckett who looked back. They both shook their heads and returned their gazes to McKay.

"Don't you see? This happened around the same time that the transporters went down. Just before the first room shut down. I'm thinking this may be some kind of security protocol. Someone not authorized is detected in the city? Shut and lock the doors, turn off the power, release knockout gas to render them unconscious, then send security go get them. Only we removed the gas, so maybe its default-"

"Is to kill if it can't incapacitate," Sheppard finished for him.

McKay nodded. "Right. Maybe just in case someone got to the machine and disabled it."

Beckett's eyes were wide. "What did we do to make the city think we were the enemy?"

Sheppard shrugged, looking at the others in the group. They were still moving along at a pretty good pace, but everyone's attention was on Dr. McKay. This really did sound like a possibility. McKay shrugged as well and started up a conversation with Zelenka about how it could have been triggered. Sheppard had to catch himself not to snap at them, thinking they should concentrate on how to shut it down instead of how it got started before he realized that one could lead to the other. He always got impatient when a dangerous situation was coming to an end. Everyone thought that he sniped and rode McKay during those times to keep him occupied and part of that was true.

The other reason was that it gave him an outlet for his energy that he couldn't use if there was no one to beat up. Adrenaline had come in handy the number of times they've had to outrun an animal, fight their way out of a village or make an end run to the gate. But in these situations it was more of a hindrance than anything, Making him jumpy and impatient.

"There!" Kusanagi shouted, and nearly bowled Sgt. Smigs over in her haste to show them the room with the balcony. They all piled, in following her to the open balcony right above the water. They were virtually in the middle of the city, but towards the outer edge, nearly between the Southern and Eastern Piers. Columns and spires stretched out above them, and out from all directions, sunlight bouncing off the windows nearly blinding. Most of what they could see looked nearly pristine in the bright daylight, shiny, colorful and clean. The only notable exception being a burned out shell of a building on the Southern Pier, twisted metal burnt black If Sheppard's memory served him that was from a dart crashing into it during the first wave of the siege. From the small part of the eastern wall still in tact, it looked to have been painted red in its day.

McKay claimed his spot on the floor gratefully, placing his data pad awkwardly on his drawn in knees, poking away and rattling off to Zelenka. Sheppard itched to turn off his radio; he was getting the conversation in 3-D it seemed with McKay both in person and over his earpiece. He knew it was only a matter of time, however, and kept it on.

Looking around at their little safe haven, he couldn't help but be frustrated that all he could do was run from the problem instead of being the solution. He was glad these people were safe, but what about those two scientists trapped inside? Were they even still alive? At least he was here with this group. If he had been trapped in the gate room watching this all of this on a one dimensional map with little glowing dots disappearing, knowing they were colleagues would have driven him nuts. He couldn't imagine how frustrating it must be for Elizabeth up there.

Now that he thought about it, he realized she shouldn't be up there. "Elizabeth?" He knew what she was going to say. But he had to try.

"Yes, John?" She asked as Radek and Rodney stopped their back-and-forth so that they could talk. "I think it's time you went on through the gate with the others. There's nothing else you can do here. Zelenka and McKay will probably have this fixed up in no time and we'll come and get you then."

McKay looked up and smirked at him. Something he must have learned from Sheppard because he never used to do that when they first met. Sheppard had to fight to not stick out his tongue at him.

"John," she said in her 'I Am The Leader Of This Expedition Voice'. "I'm fine up here. There are still people that I am responsible for stuck in this city. Including you. The jumper is on its way from the mainland. I'll go when you go." Sheppard could almost hear her 'and that's final tacked on to the end.

"You heard with your own ears, Elizabeth," he tried. "The gate room is just as dangerous as the rest of the city." McKay raised his finger and opened his mouth but one subtle lift of Sheppard's foot parallel to his ankle had him turning back to his data pad, pouting. "You are the leader of this expedition, and as such, you have a responsibility to all those on the Beta site and those on the mainland to protect yourself. So that you can be there for them whether or not this problem is solved." He nodded his head, pleased with his own logic.

"I'll go when you and those with you are in that jumper, colonel. And besides, I'm sure Sergeant Bates will keep me out of trouble," she said evenly, and he winced. He had hoped the man had enough common sense to be subtle, but really he should have known better. He'd just have to depend on him getting her out of there if things got sticky. Sheppard knew he was going to hear about this one later on.

"McKay!" Zelenka interrupted gleefully. "I think we have it! Yes, yes, security program… Something about security breach... this is it! Give me moment to go over program."

"Yes good, go ahead. But don't bother getting intimate with it, just shut it off!" McKay replied, visibly relieved. He pushed his forehead forward onto his knees. Sheppard leaned against the balcony and bumped his leg into McKay's side. "Hey, you figured it out!" He said happily. McKay just grunted, subtly leaning his weight against Sheppard's leg for just a moment before sitting up straight and glowering at him.

"Yes, I did. And that ingrate Kavanagh is going to be working on the septic systems until next doomsday for not immediately telling Radek or I about a machine that vented knockout gas somewhere in the city. I could have put that together hours earlier without the death-defying haunted house troop through the city. Before Corosen-" He stopped and winced, but Sheppard finished the thought in his head.

Before Corosen died. And just like that the relief melted away to anger that some program they hadn't even known existed had cost one of his men his life. And those two scientists more than likely by now. Jesus.

Sometimes, he thought he might learn to hate this galaxy.

"McKay. I was able to skim through most program information," Zelenka said urgently, "I cannot reset it from here. It must be set using control chair. Colonel Sheppard must get to control chair and verify security protocols to shut down system. If done incorrectly, according to information, city will attempt to overload ZPM power to act as self destruct. They used control chair to make sure only Ancients could shut down protocol, in case of successful siege on city."

Okay, sometimes he already did hate this galaxy, Sheppard thought wearily. "Can we even get there now? Do we have a way down there?" It was pretty much a straight shot and not as far as it could be, but the control chair was in the middle of the city. If any section of the hallway was down they could detour, but it might take a while. Time they didn't have.

"Nearly seventy-five percent of city has shut down but with exception of one detour, your way is clear."

"I better come with you," McKay said, dragging himself up. "May need my help."

"Me, too." Beckett said. Sheppard started to shake his head. Beckett continued, "The control chair is closer to those other poor souls trapped. I may be able to help them. I'm going."

Sheppard sighed but ignored him when he followed along behind him and McKay as they entered the hallway. "Okay, so what do I have to do once I get to the chair?" McKay was leading the way, with Doctor Beckett keeping pace with Sheppard.

"Should be relatively simple," Zelenka replied. "Just access security protocols through the chair. Only one system is active in that subset. Shut it down. That should reverse everything it's done so far."

Movement up ahead and behind him caught Sheppard's attention. He acted on instinct, grabbing Beckett by the arm and flinging him past the quickly closing door straight into McKay. He saw them falling to the floor.

There was no time for him to squeeze through. The doors sealed shut with a hiss, and he was plunged into darkness.