A/N: Written for ioweyouabourbon on Tumblr. They write lots of excellent fic too, I recommend you check them out!

This is an Agent Carter AU in which the characters are Starfleet officers on the USS Leviathan.

Please R&R.

Something deep in Lieutenant Carter's bones knew it was going to be a hell of a day from the moment she rolled off her narrow bunk. Perhaps the engines thrummed at a slightly different pitch; perhaps she had heard the hurried opening and closing of nearby doors even in her sleep. Her red uniform felt too tight suddenly, the skirt too short and the neck too wide. Her shoes pinched her feet.

To top it all off, her comms unit was making those weird static noises again, which meant that she was going to have to call up one of Krzeminski's boys to have a look at it.

No, this was not going to be a good day.

"Lieutenant Carter!" Captain Dooley barked the instant she stepped out of the turbolift. "Cover the comms."

"Sir." The bridge was chaos, which was not unusual in and of itself, but she thought she could detect a hint of urgency in everyone's voices. "Do we have a situation, Sir?"

"I don't know yet Carter. Just sit down and do your job."

It wasn't until she had slid into her station that she realized the rest of the day crew was already there. Lieutenant Sousa spun from his position at the control console to give her a sympathetic gaze, which she ignored. She certainly didn't need his sympathy today. Commander Thompson, Starfleet's golden boy, stood at attention behind his captain and ignored her. That was fine at least.

"Morning Peggy," a voice said cheerfully as she was patted her on the head with something. She reached up to grab whatever it was but only snatched at empty air. "Uh-uh Carter, this is far too delicate for your combat-trained hands."

She spun in her chair to face the voice as she arranged her headset over her ears. "Then surely our noble science officer shouldn't be using it to annoy his colleagues?"

Lieutenant Stark grinned down at her. "Touché."

"Carter!" This time it was Thompson snapping at her. "Are you getting anything yet?"

Spinning a few knobs before responding, Lieutenant Carter applied her best I-would-be-yelling-at-you-if-it-wouldn't-get-me-a-court-martial face. "Nothing, though it might help if I had any idea what I was looking for."

Thompson glared back. "Just keep checking all standard frequencies."

"Standard for what, if I may ask Sir?" Lieutenant Carter made a sweeping gesture across the many controls in front of her. "Starfleet operates on ten different frequencies, some of them scrambled. The Romulans use three besides that, and the Klingon fleet an additional five. New Vulcan has four major frequencies and two more scrambled for secret communications with Starfleet. Merchant ships could use any of a dozen—"

"All right, all right! That's enough Carter," Dooley interjected. "We get that you know your stuff. The problem is that this could be anything from a diplomatic convoy to a merchant vessel to an enemy scout. It's a black hole in our sensors and I don't like it."

"Nothing from Krzeminsky and engineering?"

"They're working on it. I suggest you focus on your own job for the time being."

Scowling, Lieutenant Carter turned back to her station. "Yessir."

The USS Leviathan followed the unknown ship's drifting movements all day. Dooley and Thompson continued to breathe down Lieutenant Carter's neck and even Sousa's puppy eyes were annoying her today. Prompted by boredom, she began cycling through every single frequency which had a chance of any traffic. This meant checking over one hundred wavelengths for a few seconds at a time, jumping back to the enemy frequencies every now and then just to be safe. The only chatter she picked up was on the general Starfleet channels and one or two communications from New Vulcan.

"Anything yet, Carter?"

"As soon as I find anything, Commander Thompson," she bit out between clenched teeth, "I will notify you."

"Tone, Carter," Dooley said disapprovingly, and she had to resist the urge to pound her fists on her console. She was sick of being treated like incompetent garbage in the job she had been trained to do. She had been first in command under Captain Rogers, for goodness's sake, and she deserved a little more respect around here.

"My apologies Captain. I missed my lunch shift and I've had this headset on all day, I'm developing a bit of a headache. Permission to visit the med bay before returning to duty?"

Dooley sighed. "Fine. Have Lieutenant Sousa cover for you, call up Lieutenant Dugan to cover for Sousa and hurry back."

"Yessir." Lieutenant Carter concealed her grin as she carried out the orders quickly and efficiently. Fabricating illness was a serious offense, she knew, but if she hadn't picked up anything yet then surely she wouldn't be missed for fifteen minutes. Besides, she needed a good vent if she was going to spend the rest of the day trying to identify the mystery ship.

Sure enough, Angie Martinelli, senior nurse, was on duty in the med bay. She waved cheerfully as she saw Carter enter. "Afternoon, English! What brings you down here?"

"Headache," the Lieutenant explained, rolling her eyes to make it clear that this had merely been an excuse.

Dr. Jarvis emerged from another room, looking stern and wiping his hands on a towel. "Now Lieutenant Carter, fabricating illness is a serious offense."

She ignored him except for a sideways glance and he disappeared once more. They were good friends—it often took both of them to contain Stark's insane genius—but Jarvis knew better than to tangle with her, especially when she was in a bad mood.

"What's up, Peggy? You look like you're not feeling too hot," Nurse Martinelli asked, frowning. "You're sure there's no headache?"

"No, Angie, though I appreciate your concern. It's just been a long day."

"Which is code for 'Thompson's being an ass,' am I right?"

"Maybe." Lieutenant Carter couldn't hold back a smile at how well her friend knew her. "He and Dooley have me scanning every conceivable frequency while we just follow an unknown ship around. They're looking for a transmission but I don't have anything to go on. Unfortunately they don't care. They still expect results."

"Well that's a load of—"

"Angie!"

The nurse shrugged, grinning. "Look, I know they're your superior officers but they've gotta show you some respect! I mean, if Captain America had you as his right-hand woman, why can't they see that you're got some skills?"

Lieutenant Carter sighed, but before she could respond the comms unit a few feet to her left emitted a loud burst of static. Nurse Martinelli strode over to it and smacked her hand against it a few times.

"I've told Krzeminsky a hundred times to send one of his engineering boys up here, but this damn thing just keeps doing that!"

Dr. Jarvis stuck his head around the corner. "But he did send someone up. They were here just this morning."

"The one in my room has been giving me trouble, too," Lieutenant Carter mused. "It seems like this whole ship is on the fritz lately. Maybe there isn't even a ghost ship and our scanners are just—" Her gaze snapped back to the comms unit.

"Peggy? What's wrong?"

"Nothing's wrong, Angie!" Carter yelled as she flat-out ran from the med bay. "My headache is gone! Thank you!" Her voice faded as she snaked through the corridors back to the turbolift.

By the time she made her way back to the bridge, her face was flushed and she was panting slightly. Captain Dooley and Commander Thompson both turned to see who had jumped out of the lift before the door even had time to open properly.

"Carter?" Thompson was the first person to find his voice, as usual in any situation where there was sass to be provided. "Headache better?"

"Much. Pardon me, Daniel." She didn't wait for her colleague to move from her seat but instead leaned over him to fiddle with various switches and knobs, much to his apparent discomfort.

"Would you mind telling me exactly what you're doing, Lieutenant?" Dooley finally asked irritably, but he was answered when a crackling static came over the bridge's sound system. It was interspersed with occasional squeaks and chirps which had no recognizable pattern. The usual chaos of the bridge quieted to a general confused murmur.

Thompson strode over to the communications console, which only served to further crowd Lieutenants Carter and Sousa. "Are you picking that up from the ship?"

"Actually," Lieutenant Carter muttered, "this is the frequency we use for internal shipboard communication. No one reported it because they thought the comms were just malfunctioning."

"So they're using our internal frequency to communicate?"

"It would appear so. Now we just have to figure out what this means…"

"Not bad, Carter. Not bad," Captain Dooley said with something like wonder in his voice.

Sousa managed to extract himself and step away, leaving only Thompson to lean interestedly over her. "What're you doing now?"

"Trying to isolate the actual communication from the static. Meanwhile, I need a linguistics team on standby for analysis," she ordered without a second thought.

Commander Thompson stiffened, unsure how to respond to a command from her. He glanced at Dooley, who nodded. "Aye, Lieutenant."

Hidden behind her hair, Lieutenant Carter smiled.