Whispers from the past

We try to pry the door open, but to no avail. I can't say whether that is because it's locked or because it's too old, but either way, the door appears to be shut tight.

I sigh, "Great, finally signs of civilization and we're getting shut out..."
"Maybe if we make enough noise someone from the inside will open up?", Nym suggests.
I look around and ask, "Nym, your optimism is really refreshing, but this is Tisis and an asteroid came crashing down just recently...tell me, if you were them, would you open that door up for anyone? I mean, chances are, and that's only if there's someone in there, they don't even speak our language. For all it's worth we might well be savage beasts to them."
Nym hangs her head and asks, "...but...but..."
"Look, I never said we were going to give up. I just said that we shouldn't count on someone else who might potentially be there. It worked up to now, so why change it, right?"
Nym raises her head again and nods at me with a smile.

I scratch my head and look at the well hidden door, wondering how we could open it.
I examine the door thoroughly, but while it's apparent that the door is there, there doesn't seem to be any way to actually get it open. I can make out the traces of the door hidden within the woodwork, but the door fits so perfectly into the frame, that it'd be impossible to get anything in between to use as a lever.

Suddenly Nym says, "...oxygen."
"...pardon, what was that?", I ask, looking up from my thoughts.
"Whoever is in there is bound to need air to breathe. And that air needs to come in from somewhere.", Nym explains her thought, looking far away, apparently pondering our options.
I think about Nym's words for a few moments and then begin to understand what she's trying to tell me. There might be another entrance. One, where the air is pumped into this bunker...but where would it be? And what if it's too small to fit through?

Suddenly a thought shoots through my mind and I ask, "...that reminds me...how did we have enough air on the ship?"
Nym says, slightly absent minded, "We recycled the air by breaking the CO² you were exhaling into their carbon and oxygen molecules respectively. After that, we mixed in a few other molecules to simulate the air on Earth more accurately. But I don't know the exact details. Though I think the greenery in the garden also helped."
I mutter, "Sure does sound very detailed to me..." before saying more loudly, "...and...what if the people in this bunker do the same?"
"Not likely. It's a very energy intensive process which requires a large power source, which is only present on large spaceships."
"Still, how is that unlikely...?", I keep probing.

Nym sighs, "Because there's oxygen all around us, Sirus. Why would anyone put a huge ass generator and a molecular mixer into a bunker, if there's ample air around them?"
"And...what if they didn't breathe air? What if they breathe...oh I don't know, water?"
Nym chuckles, "If you're thinking about fishes, those breathe oxygen too. They just filter it out from the water. But yeah, I know what you mean...if they have indeed created an artificial atmosphere in there, it might be genuinely dangerous for us to enter...well, for you more than for me, actually."
"How so?", I ask curiously.
Nym points to her chest and says, "I have lung implants which filters harmful substances from the air for me. You don't."
"...wait, why would you have such a thing?", I ask, genuinely confused.

Nym smiles a little as she sits down at the base of the tree and says, "We all did. I think it's because we...the Asmodei...aren't suited to breathe the same air you do...at least not for extended periods of time. My teacher once told me, that the air of Terra was so laden with toxic substances when my ancestors arrived, they couldn't even take a single step from the sealed interior of the arks without protective gear. Your people on the other hand seemed to be doing just fine."
I lament, "Yeah, we've always been a sturdy bunch I guess."

After hanging after the thought for a little while, I sigh again and say, "It'll be night again soon. If we're going to look for some alternative entrance, we should hurry up. Either that or we need to find another shelter for tonight."

Nym nods in agreement and we begin searching again. All the while, Sera is grazing peacefully, while Ray is playing around. As the sun finally sets, we get back together to tell each other about our finds.

I say, "I found a small cave about ten minutes from here. There we should be able to spend the night. But other than that, I got nothing...what's really odd though...I haven't seen a single animal all this time...except for our two, that is."
Nym shakes her head and says, "Me neither...now that you mention it, that is strange. It's also...unusually quiet...something feels wrong..."

I shake my head and say, "Let's head over to that cave and set up camp. Whatever is keeping the animals away from here didn't kill us yet...say that implant of yours...does it alert you of toxins in the air or something?"
Nym caresses my cheek and says with a quite voice, "Don't worry, Sirus. You'll be fine. And if you don't wake up tomorrow, I'll make sure to feed Ray your remains."
A mischievous smile sits on her face as she says that and I punch her lightly with a smile of my own.

And thus we pack up to move to the cave, our stomachs growling dangerously.
However, just as we want to wander away, Ray suddenly runs off.
I shout after him, "Hey Ray! Come back here!", but Ray doesn't listen.
I sigh, "Sorry, Nym..."
"Don't you think he'll be fine?", Nym asks a little annoyed.
"...probably, but he wouldn't run off like that for no reason. I want to see what that reason is. I mean, it could be dinner!"
Nym sighs, "I guess that is a fair enough reason...okay, I'll wait here. Don't take too long, okay?"
I nod, "I will." and begin to run after Ray in the light of the setting sun. Fortunately his trail is easy enough to follow, especially since he's barking quite loudly.

When I finally find him, he's sitting in front of a hollow tree, barking at the hole at its roots.
I sigh, "Listen Ray, if you want to go hunting, it really doesn't work that way. I mean, how am I supposed to get whatever is hiding in there now? Not even you fit in there any more. You need to cut off the escape route of the prey, so I can go for the kill while it's in the open and..."
Suddenly Ray barks, "Stale air! Coming from here!"
I blink a few times and then go over to the tree. And indeed, the air coming from that one does smell a little funny.

Following my intuition I knock against the tree and without much surprise realize that it too is made of metal. Ray found the exit point of the ventilation system...but there's still no luck, since the entrance is way too small for Nym, me or even Ray to fit through.
I tousle through Ray's fur and say, "Good job, Ray. But let's go back now. Nym is waiting. And we don't want her to worry, do we?"

We trail back to Nym and I explain to her what Ray found.
Nym asks, "The exhaust point is all the way over there? Impressive..."
"...how's that impressive?", I ask, as we're heading towards the cave.
"Well, it goes to show just how large the base beneath our feet has to be."
"Oh, now it's a 'base'?", I ask.
Nym nods and says, "A bunker is an emergency shelter. Comparably small dimensions with only the essential necessities, to prevent detection. A base on the other hand is a large complex, with everything you need to really live in for an extended period of time."
"...and that changes things...how exactly?", I ask.
"Not very much I'm afraid...you said the exhaust point was too small for any of us to fit through, yeah?"
I nod in agreement.
"Well, bummer.", Nym sighs.
I say, "Well, Ray might fit, but what would he be doing in there?"
"...true enough. Plus, we don't know if the ventilation system is a one way street."

After reaching the cave I had found earlier, Nym prepares a fire, while I collect a few herbs from the vicinity to at least eat something.
Over dinner, we talk about what we found, but one thing's for sure.

We need to get into this base or bunker or whatever Nym wants to call it.