"Who are you and how did you get down here?"
Three pistols target Adelaide's vital points. The OEI agent lifts her arms and shows the Foundation agents her empty hands. "So, this is going to sound really weird," she tells them. "But hear me out. Okay?"
O5-5's expression does not change. Her scowl looks as if it has been carved down into the very bone. "I will not ask you a second time, child."
Adelaide takes a long, heavy breath. She begins: "I work for the OEI — Office of Exoversal Intelligence. I'm here to figure out why —"
"No such thing. Kill her."
— damn it.
BANG.

"Who are you and how did you get down here?"
Three pistols target Adelaide's vital points. The OEI agent lifts her arms and shows the Foundation agents her empty hands.
Adelaide takes another long, heavy breath. She tries again: "I work for the Office of Exoversal Intelligence, and yes I know you've never heard of us. I need your help to figure out why —"
"You're lying. Kill her."
— damn it.
BANG.

"Who are you and how did you get down here?"
Three pistols target Adelaide's vital points. The OEI agent sighs, lifts her arms, and shows the Foundation agents her empty hands.
"I work for the Antimemetics Division," Adelaide lies. "I'm here because —"
"Nice try. Kill her."
— oh come on!
BANG.

"Who are you and how did you —"
Adelaide falls to one knee and opens fire.
The first two rounds cut through one man's torso and windpipe, exiting in a blossoming pink-red cloud of viscera. The third strikes the other man right between his eyes. They both drop.
She pumps round after round into the last man's chest, but he doesn't seem to mind. She rushes him just as he pivots and takes aim.
Right for her face.
— sonofa —
BANG.

"Who are you and —"
Adelaide drops the first two and charges for the third, popping him a few times along the way. When she feels her shoulder hit his chest, she realizes why the bullets didn't work: Some sort of body-armor. So, she tackles him to the floor, smashes his nose in with the butt of her pistol, then finishes him off with two to the face.
Adelaide turns and aims her pistol at the old woman on the other side of the bunker. Just in time to see her lifting the first man's pistol and aiming it straight for Adelaide's head.
Adelaide rushes forward and —
BANG.

"Who —"
Rinse and repeat. Addie drops the first two, tackles the third, then buries two rounds between his eyes. This time, she doesn't even stop to turn; she just hurls herself at O5-5 the instant after she squeezes the trigger.
Whump. Adelaide hits her hard. The old woman drops the pistol. Her nose gives way beneath Adelaide's elbow, making a nasty sort of crrnch. O5-5 falls, wheezing for breath. Adelaide follows. Once she's got her pinned, Addie nudges the barrel right under O5-5's chin:
"Adelaide Vagrante. I used an extremely dangerous short-range teleporter. Next question?"
O5-5 splutters through a steady trickle of blood. "— nngh. Insurgency?"
"No. Foundation. OEI — Office for Exoversal Intelligence."
There's a long, awkward stretch of silence. The only other sound is O5-5's ragged breathing. Then, at last:
"'Exoversal'."
"Yes."
"You just made that word up."
Addie shrugs. "Technically, all words are made-up." She nudges the barrel a little closer. "You really wanna debate etymology with the lady pointing a gun at your head?"
"You killed three of my men."
"They killed me first. Besides, we both know they'd be dead in about three minutes anyway. Right?"
O5-5 tries not to let the surprise show, but Adelaide catches it. Just a little twitch of one pale, well-plucked eyebrow. "So you're aware."
"That this world is about to end? Yeah. I'm 'aware'. Think we can have a nice, civil little chat about it, now?"
"Given the fact that we only have three minutes before it happens, any such 'chat' would have to be —" O5-5 stops, then blinks. "Wait. This world?"
Craaaap. "I mean, Mars is gonna be fine, yeah?"
O5-5 narrows her eyes.
Yeah, she's not buying it. Adelaide sighs. "Okay, fine. You caught me. My department isn't from this universe. I'm on a recon mission. We want to know what happened — so we can make sure it doesn't happen in our universe."
"You're from a Foundation agency in an adjacent universe that investigates universes where we failed." She doesn't sound angry. More irritated. Probably disappointed she didn't think of this first. "How do I know I can trust you?"
"You don't, it doesn't matter, and now we've got two minutes left." Adelaide tries her best not to sound frustrated. Explaining this to every single O5 she meets gets a little old. Just once, it would be nice to visit a dying world where they actually had an Office of Exoversal Intelligence.
Of course, those worlds are probably the ones that survive.
"Explain how it works," O5-5 says. "Make me trust you. And I'll tell you a pass-code you can use on your next iteration to convince me to believe you immediately."
Adelaide opens her mouth, closes it, then opens it again: "Wait, how do you know about —"
"Surgical scars along your wrists and neck. Predicting our actions before we take them. Mentioning my men previously killing you." Crap. She's sharp. "We had a project back in 2005. Temporal displacement matrix wired into the central nervous system. Lets you overwrite your past-self with your present-self. You know that it's effectively a death-sentence, don't you? Every time you 'leap' back to a previous state, you're —"
"Life's a death-sentence," Adelaide cuts her off. "Tell me the pass-code."
O5-5 rolls her eyes. "'There is no Site-5'."
"Okay." Adelaide lowers the pistol and shifts her weight off O5-5. She stands up, then reaches down and helps O5-5 to her feet. "You got about one and a half minutes before your world ends. What do you want to know?"
O5-5 asks her questions. Adelaide answers them.
Approximately 90 seconds later, the world ends.

"Who are you and how did you get down here?"
Three pistols target Adelaide's vital points. The OEI agent lifts her arms and shows the Foundation agents her empty hands. She smiles:
"There is no Site-5."
O5-5 tilts her head. She stares at Adelaide for quite a while. Then, finally, she speaks:
"I have no idea what that means. Kill her."
— oh you have GOT to be kidding m —
BANG.