(Lacking direct interaction to write this, I have of course made some likely glaring assumptions about Yonca’s willingness to participate in this endeavor, and in her aggressively stoic conversational style. I imagine, however, that some form of the following story is hopefully reasonable, tweaked to how your choices would have shaped different pieces of the vignette.)

Reeling from waves of intense vertigo you make your way from the commons car towards the forward sleeper car in search of your room and med kit. From behind you a great explosion rings out, glass shattering out of all the cars windows. Briefly, the night outside becomes day, a strobe of intense light blanketing the jungle’s features. Ahead of you another figure stumbled into view in the hallway. Sebastien. He’s surprised to see you for a moment, then gathers himself and shouts:

Come! We haven’t much time. The others are in some kind of torpor. Something is terribly wrong, we must get off the train at once!

All at once the train shudders again nearly knocking you both from you feet. The pilot must have hit the emergency break. Through the remnants of the windows the howling wind is replaced by a horrific shrieking wail of steel on steel. Curtains of sparks erupt to either side.

You find your nausea subsiding with a rising hit of adrenaline. Seb grabs your shoulder, and as reassuringly as he can yells over the din:

Please, trust me. I can explain more later, it won’t be safe for us.

He pulls you out onto the gangway between cars. The reassuring hand appears again, but for a moment you think you are betrayed as he soundly shoves you outward, off the small strip of solid ground.

Tuck and roll!

Just before you hit the ground you see him leap after you, bathrobe fluttering in the wind. You both come to a rolling stop in loamy ground beyond the tracks. The Incunabulum roars away in the distance, a firing spectacle hurling itself deeper into night. Unnatural quiet seeps in around its echoes. Looking back the way you came you can see a column of static lightning rising high into the sky some distance away. It is already fading, white to yellow, edges tinging further to orange. More like the an after image than the real thing, it hands there unmoving, an impossible rend in the sky.

Do you know where we are? No? Excellent. Neither do I. We’re all set to find it now.

Hearing this nonsense, you come to the realization that Seb was more lucid than ever before in the moments on the train. Now, however, he seems to be returning to form…

This way this way, let’s put some distance to the tracks. I’m sure our entrance will have turned all the wrong sorts of heads. What were those bastards thinking?

He strikes off perpendicular to the train, heading South into thickening jungle. The light here is strange, it has a bright twilight quality, but the only source of illumination is the moon. It hangs, full, nearly directly overhead. A disk that, in your scientific opinion, is quite a bit too large. The undergrowth thickens, but remains navigable. All of a sudden, Seb comes to an abrupt stop and you realize that you must have fallen into some sort of trance while walking. It is unclear how long you’ve been pushing through the trees, and a glance behind you reveals no memorable landmarks.

Seb unblocks your view, sliding down a short embankment and thoroughly muddying his clothes. Peering down, you see a small clearing formed around the emergence of an underground stream as it begins to snake a lazy path through the forest. In the clearing, Seb wades through the ankle deep water towards… a door? Yes, that’s quite what it is, a simple wooden door nestled into the dirt side wall.

Throughout the sunken clearing, a smattering of poles have been driven into the ground, each bearing a crimson ribbon fluttering gently in the breeze. Seeing these gives you an intense feeling of unsourced deja vu. Following after Seb and getting closer to the door, you notice it has a carving of a tankard on it, in the Teutarch style (if Yonca has seen the tankard penny, it is an exact match) though otherwise bereft of adornment. As the two of you reach the threshold, Seb leans in:

I, uhh, am not exactly sure what we’re about to see. This place, I’ve seen it in my dreams before. In my, visions. The times I am most lost, as the nightmares are at their darkest I always seem to find this door. It… wanders.

He pushes the door open and waves you inside. The interior is expansive, though somewhat maze like, and appears to be made up of a large patchwork of historical styles as if the bar had been partially renovated hundreds of times over. The whole scene is lit by a medley of different sources, from piles of flickering candles to gas lamps to modern arcane lightning tastefully brightening corners.

You overhear a gentle babbling of many muted conversations echoing around the walls. Many languages, far more than you recognize, make up the murmurs. Tucked away private alcoves comprise most of the available seating, all with privacy curtains. Pushing deeper in you find a central chamber amongst the layout with deeper floors and a raised ceiling. Intricate mosaic tile work runs along the floor evoking tree roots, and from the middle of the room sprouts an intricate silver facsimile of an ash tree, rising to fill nearly the two stories up to the ceiling. Hanging from the branches are innumerable bottles of wine and spirits. Draped throughout those same branches lies an enormous anaconda, its body pitted and scarred, though its scales still hold healthy luster.

As you enter, the snake is finishing a pour into the waiting goblets held by a patron below. On tip-toes they lean up next to the anaconda’s head and whisper something to it, before departing to a shadowed table. It’s forked tongue flickers out, then it turns towards the two of you.

Ssssssebassstien. A guesssst made alwayssss welcome. Tweaked the formula again? Your luccccidity ringsss clear thissss night. What to drink?

(You hear and understand these words, but you can tell they are not in a tongue you recognize. Rather, the words themselves are almost instructions of their own comprehension. A meta-language imparting new meaning on its path between your ears. It still, in places, has sibilant tones which become emphasized as the anaconda speaks them.)

Seb looks around almost sheepishly, then leans in and unleashes a rapid explanation in french. The snake trains its unblinking eyes on you, its tongue tasting the air, while Seb goes on at length, presumably bringing the creature up to speed on your situation.

(This is as far as I got with fully written narrative, I would have preferred to finish this but, instead, here are the notes…)

• Talking with the serpent you learn that this space is visited by some spirits on their way to their final task. Final-meal-before-execution kinda thing.
• Customary payment of one’s tab here is a report from the outside world. Secrets / news / gossip, the serpent wants to hear it all.
• You learn that Costis stopped off here, and offered the serpent quite a secret in return for a deal - get a message out to his only trusted colleague about the location of stashed world-tree-sap in exchange for information about the Crown’s dealings. “a regular” (the serpent will not elaborate) sent Yonca the coins in hopes she’d end up finding the bar.
• The serpent passes on a note from Costis: it details where he left the world tree sap, and probably something of an apology for getting mixed up in Crown work (though I am making some assumptions on Costis' motivations). Imagine if Costis was given a chance to write this note, but forbidden from discussing the crown’s use of spider-based hypnotism.
• Seb mentions needing to stay a little longer to “pay up”, but that when you leave, this place had a magical effect “putting people right where they need to be”.
• If you would resist leaving before Seb here, there’s some more we could talk about
• Otherwise, when you leave, the door leads to a different place than you entered. This time it is embedded in a large rock, the remnants of some aeons old rockslide down a hill, long since taken over by trees. Below you down a gentle slope and off to the side you hear the noise of a train speeding up.