A/N: Kudos to whoever gets the reference I made in the title right off the bat.

Yeah, I should be working on my Assassin's Creed fic, but I hit midterms and a wall labeled 'Writer's Block' and the plot generator in my brain started spitting out Star-Spangled-Man-With-A-Plan-themed stuff.

Thank you, Dad, for hooking me on Agents of SHIELD and Agent Carter and inspiring me to rewatch everything in the Marvel Cinematic Universe because I have a fetish for interlocking timelines.

This prologue is a little short, only a thousand-ish words, and really pathetic in terms of dialogue but...oh my god that is a dissected giraffe please please stop fondling that laryngeal nerve people never ever take biology if you are squeamish.

...let's just get on with the story. I need to find a toilet in which to vomit.

Disclaimer: Screw disclaimers. I know I don't own the Avengers. I know I don't own Agent Carter. More importantly, you know I know. Most importantly, I don't own Chris Evans, which really, is the greatest tragedy of all.

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The Longest Day

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Prologue: A Day in the Life, 1946

It had been, decidedly, a long and taxing day for a certain Agent Peggy Carter.

First, the radiator in her brand new flat had started malfunctioning in the early morning, heating the flat to boiling. Flinging open the windows hadn't helped much, as a heat wave had hit the city the day before, bringing her bedroom down from 'volcanic' to merely 'scorching'. The walk to work had been been utterly miserable in the heat, even in the lightest of her dresses, and the calluses on her heels had given with sweat and transformed into blisters thanks to her nylons and heels. She had practically hobbled into the SSR, and had been briefly relieved by the fact that all of the switchboard girls looked just as bad as she felt. Even normally-cheerful Rose could only give Peggy a weary nod, dabbing her sweaty forehead as she buzzed Peggy in. Peggy had straightened, ignoring the pain in her feet, and strode in- the other agents' misogynistic tendencies hadn't ceased with her prodigal return after defeating the Leviathan doctor who had killed Chief Dooley, and hell if Peggy Carter was going to show a shred of weakness to these lunkheads. Well, lunkheads and one gentleman, she amended, as Sousa had welcomed her with a warm smile and an offering of ice water. Her good nature abruptly ended, however, as another agent swept past, sending Sousa stumbling into her just as she tilted the water back. While the ice water was lovely on her sweaty skin, it was decidedly unlovely on her dress. She swore vehemently before brushing of a blushing and stammering Sousa and marching to the locker room past laughing agents. Really! It was if they were all children! To make matters worse, the spare blouse she had tucked away was white, and her brassiere was both damp and black. Blushing furiously, she walked back into the bullpen, greeted by wolf whistles. She snatched up Sousa's discarded sportcoat and buttoned it over her now see-through blouse as she made her way to her desk, refusing to look at the red-faced man. Of course, the moment she sat down, Chief Thompson-ugh, that was still galling, even if his attitude towards her had improved somewhat-emerged from his office and set a tall stack of files down on her desk with a terse "Look into this" before vanishing back into his office, where a suspicious humming was emanating from. If that bastard had a fan-! She had shaken her head and muttered dark things before buckling down on the paperwork. Leaving aside still-intermittent coffee-fetching, paperwork was Peggy's least favorite part of the job. Give her a few clues, a gun, and someone to chase, and she was happy. While an excellent analyst, she just couldn't bring herself to enjoy deskwork like some paperpushers she had known during the war. And now she had a whole stack of papers to push around.

Things had started to look up around closing time- the papers she had been sorting through all day actually helped her determine that a pattern of Leviathan dead drop locations and pick up times around the city, with the closest drop only a few blocks away, and the likely pick up being later in the evening. She hesitated only briefly before leaving the office alone, pistol tucked into the back of her skirt. She had a bad habit of trying to take things on alone, something she had been trying to break herself of, but this time, she was only doing some observation. If everything went well, no back up would be necessary. Nevertheless, she wrote a quick note on Sousa's empty desk explaining her plan before heading out.

Locating the dead drop had been a bit of a task. Based on her analysis, she could figure out the block the drop was located on, but not much else. Dead drops were meant to be entirely inconspicuous to the common observer- only a person who knew what they were looking for would be able to identify a drop location. Peggy had no idea what she was looking for, and she couldn't very well peek into every nook and cranny on the block without either getting arrested or attacked, she was quite sure. She opted to wait for the Leviathan operative instead, and luckily, people-watching from an optimally placed bistro with tables outside was far from suspicious. Unluckily, it meant she would be missing dinner with Angie, and while the waitress/actress was generally understanding about the nature of Peggy's work these days, when push came to shove, she was a civilian with a normal schedule-a normal schedule that included twice-a-week dinners to work with Peggy on her new open-and-honest policy. That, and the fact that is was still positively roasting, even as the sun began to set, and there was no way that Peggy was taking off her ill-gotten sport coat to reveal either her underthings or her weapon in public, no matter how miserable she felt. And she was feeling absolutely miserable an hour later as the streetlamps flickered on and the waiter began to shoot her nasty looks. Taking that as a sign to leave, Peggy stood, just in time to spot what was undoubtedly the operative she was looking for. Who else would be wearing a trenchcoat in this heat? She made her way down the street parallel to the operative, watching in her periphery as he approached a mailbox and stopped. She kept walking a ways more before stopping and pulling a compact out of her purse. Watching in the small mirror, she saw the operative open a panel on the side of the mailbox and withdraw a small wrapped item. A secret compartment in the mailbox then-not the most original of drops, but still effective. She snapped her mirror shut and began to carefully tail the man. She wanted to know not just the location of the drop, but the location of the Leviathan safehouse the operative was taking to which the operative was taking the package. Perhaps the day could be salvaged after all.

A few hours later, she reevaluated her opinion and rather grumpily called it a loss. The operative must have noticed he was being followed, or the SOP for Leviathan operatives post-dead drop retrieval involved criss-crossing Manhattan for ages before returning to wherever they came from. Either way, her feet were throbbing and she was sweaty and exhausted and absolutely sick of this unbelievably bad, unbelievably long day. Luckily, though, it was almost over. She checked her watch, before glancing back at the still-walking Leviathan operative- nearly midnight. Six minutes till a brand new day, hopefully with little in the way of brand-new problems.

And of course, just as a tiny spark of hope for a better day tomorrow flared within her, the Leviathan operative stopped and turned to face her, looking unerringly at her through the crowd of people and cars that still hustled through New York City this late at night-particularly in this locale. Peggy apparently had followed the operative to Times Square, a familiar landmark, and certainly not the best place for a confrontation. She narrowed her eyes and palmed her gun, scanning the crowd in case of back up. Surprisingly, she didn't see anyone moving to support the operative, or even anyone who looked to be potentially dangerous. Her eyes returned to the operative. His head tilted back slightly in a clear challenge. Relatively far away as she was, Peggy could still see the scar that came from the removed voice box with the shift of the man's collar. Another Finow veteran, then. Positively wonderful, that reminder of Doctor Ivchenko.

She approached slowly, hand poised behind her back, ready to pluck her pistol from her waistband and shoot in an instant. She stopped a good ten feet from the man, favoring caution. The flow of the late-night crowd continued around them unimpeded, but seemed to instinctively veer away from the gap between Peggy and the operative, leaving them in their own little bubble.

"How did you know I was here?" Peggy asked casually.

The operative slowly pulled out a hand-held vocoder and held it against his throat. "Recognized you at drop. Preferred not to engage. You are persistent, however," he said in a familiar mechanical croak.

"That I am," admitted Peggy. "I couldn't very well let you slip through my fingers." She shivered slightly as a cold wind blew out of nowhere, drying her sweaty skin instantly to freezing. Thunder crackled far in the distance. A storm was blowing in, no surprise, considering the earlier heat.

The Leviathan operative gave a rather macabre grin. "So have discovered. Cannot permit follow."

Peggy arched an eyebrow and coolly pulled her gun, expertly training it at center body mass. "If you won't allow me to follow you, then I suppose I'll just have to take you in." Someone in the late-night crowd spotted the gun and let out a scream echoed by thunder, which seemed nearer now.

"Cannot permit," said the operative again, still grinning. "Leviathan rises, Agent Carter."

Things seemed to happen very quickly, then. Before Peggy could pull the trigger, the man smashed something small and glasslike against the pavement. She lifted her sleeve to her face to prevent inhalation, but no gas appeared from the shattered whatever-it-was. Rather, it pulsed with yellow light, disturbingly like the grenade she had once so painstakingly disassembled. Fear flashed within her, as she recalled the bombings at the Roxxon plant and the bay-had the operative made some sort of suicide play? The yellow light pulsed faster and more intensely at her feet, and she turned to run, a scream of warning on her lips.

It never came. Instead, everything flashed an intense, blinding yellow for a single instant. Lightning crackled through the sky, followed shortly by the boom of thunder. The skies opened up, and across the city, bells tolled midnight.

But no one was there to see the start of the new day. Times Square had emptied with the coming of the first few drops of rain. All that remained was a black scorch mark, easily ten feet wide, on the pavement. Agent Peggy Carter and the Leviathan operative had simply...vanished.