Gas! Gas is pouring in thru that odd vent and pouring onto the floor, slowly filling the room! This is a trap!
You are not surprised to hear the click of a lock behind you, nor to see that the walls here are solid, nor that there is a ceiling here, which is merely disguised to look like it was open. In the back of your mind, you briefly wonder how many people they have trapped here. There can’t be too many people like you, people who have a lot of enemies, one of which is willing to go to extreme lengths. Once, they can just claim you left and went to some dangerous place. Three, four times? Nasty questions get asked and they end up suffering whatever fate awaits you. But maybe peasants? The city can be very dangerous to the newcomer. So they offer this newbie a job, which turns out to include cleaning out this stable and before too long he or she is a helpless prisoner, likely on the way to becoming a cowgirl and nobody need have any idea they ever came here. Still stupidly dangerous in your opinion, but you can see how it might be done to get a full supply of cowgirls at a low price without anybody suspecting. It’s an idea that might appeal to somebody who is clever rather than smart, that wouldn’t realize that eventually something would go wrong and everything would come crashing down, such as when they try this trick on you. But now you get to work making sure they do not add to their list of victims.
Step one, you quickly gather up an armful of straw from the floor [which is already covered by the gas]. It’s not perfect, but it’s the best you have. Holding your breath, you stuff it into the vent. There! It’s far from perfect, but you have at least doubled your time you have to escape. [But you can no longer see your ankles. When it reaches your face …]
How? You are in a locked box after all. How can you get out where surely several others have failed? Well, those were likely confused peasants with no idea of what was going on, not a seasoned adventurer who had broken out of more than a dozen deathtraps like this. [Technically, this thing is supposed to capture you alive, but you doubt the difference is important to you just now.] There should be several ways to get out.
Where? You give everything a closer look. The walls? They were clearly built to hold in a cowgirl. With four legs and all that lower body, she could blast thru a wall that you could barely budge … No hope there … But wait! … Yes, this was once just a normal cowgirl pen, and you don’t need solid walls to keep in something as big as a cowgirl. There were gaps, big gaps if you were talking some as small as a human. And they had sealed these gaps with cheap plaster. This is going to be rough, but …
Your shoulder slams into what you are hoping is a soft spot. [You really wish you had a shovel or something, but of course they had not left anything of the sort in here.] You get your wish, sort of. At least you do not break any bones. But they had needed some sort of form to keep the plaster in place, and that does not shatter. So you must slam again, and again. And watch that gas creeping up your legs. You don’t have much time.
But finally the wall breaks, a little. There is a hole out. Great. There are also several people waiting for you to try to exit. Not so great. You can surely take most or all of them in a fair fight, but while trying to wiggle thru the little hole? They will have loads of time to pound reason into your skull. Well, at least the gas is sliding thru the hole, so it won’t get above your waist, at least not for some time. So where to try next?
The gate is the obvious choice, but it surely was also the choice of those unfortunate peasants who didn’t get away. That means it has likely been enforced and any flaws corrected. Doesn’t sound good, but the peasants didn’t have your talents at escaping, so they could have overlooked something…
How about the roof? Surely not many have tried it, but that is going to be a difficult climb, and who knows what you will find? Of course, that includes both good and bad, but it’s not really a choice you would make, except that there are not much in the way of alternate choices…