She walks up to the counter and examines it. There's nothing behind the bar where you would normally expect shelves full of alcohol, and nothing on the bar where you would expect a cash register or something, and overall this whole place gives off an air of "faked up to mess with people without a ton of attention to detail".

When she gets close enough to touch the bar a napkin appears on its surface, suddenly and silently as though added between frames in a movie.

Okay, so someone is watching and capable of teleporting things in here. And the thing they chose to teleport was a napkin. For some reason. She picks up the napkin and examines it.

It says Welcome to Milliways! Can I get you anything? The first drink is free.

"Hey, uh, I never got your name, also there's a magically appearing napkin offering us free drinks and not explaining why we got kidnapped." 

"Ismat. Uh, I don't have anything on me for detecting poison."

I'm sorry, I don't control the behavior of the door, says a new napkin. It seldom declines to open for a given patron for more than a subjective day. I don't dispense poison, though I have nothing but my word to offer on that.

"Yeah, me neither." Margaret hands Ismat both napkins and checks if her phone has signal.

It does not.

"- well, who does control the behavior of the door -"

It's conventional to refer to them as "the Landlords" but I can shed no further light on the matter.

"So you're, what, trapped in here with us too? Where are you, why are you communicating by napkin?"

I'm the bar. I'm stationary by nature and this is how I communicate with most patrons.

"Oh! Sorry, I didn't realize people came in bar. Did you know people could be bars, Ismat? Also, uh, bar, how long has this place existed? Have other people come in here?"

"I don't know of anybody making a habit of turning people into bars but it's not the strangest thing I ever heard."

There's usually someone around, but I'm afraid I have very little idea how old I am, I simply can't remember back that far.

That sounds pretty unnerving for the bar too. "So, uh, I still have no idea where Osirion is."

"North end of Garund."

Ugh, American schools are really living down to the stereotype today. "Where is that relative to North America?"

"What's North America? It's, uh, south of Avistan, west of Casmaron..."

"Okay, if it weren't for how you're speaking English I'd be wondering if you were even from Earth."

"I'm speaking Taldane!"

"Oh, man, translation magic? I wish I had found out that was a thing sooner! And not like this."

"It's a thing, but - I didn't do it, I don't go around wearing something that does that -"

The two of you are not from the same world, says the bar, if anybody's looking.