So I'm trying to set up this fantasy story... In the first couple of chapters there is a war, and the leader of "the bad guys" (if I may simplify it) is crawling into some tunnel under a small castle and sort of "locks" the hideout or just closes it and makes sure it's well hidden. I need to think of something that on one hand would be a sure way to hide (after all, he has been planning it for a while) but on the other hand, would be found quickly (I need the good guys who are roaming through the castle, looking for him, to find him rather in a hurry and storm the tunnel. There is another plot line, with other characters, that involve a person trying to get the old blueprints to a city. I suppose that the blue prints, made by an architect who is long gone, can also include the surprising blueprint of the castle. I need the places of the two plot lines to be far from one another, in either different times or different places in the world, because the first plot line happens in the snowy winter and the second one in the summer. And I don't wanna rip off George R. R. Martin. (If you want to reference Martin, please no spoilers. I'm still in book 1. Please no spoilers). It's a world that has griffins and dragons, so I suppose the blueprints can be flown from point A to point B. Still brainstorming it with myself.
Well, we're talking about someone who had time to plan this. The point was to create a room that would not be found. So something like a draft means that those who planned the room and those who paid for the room didn't take the draft into consideration. It's a cool plot device, and one that I might even use in the future, but it basically makes my characters non-perfectionist, who didn't think it through. That's not who they are. But now you raise a new and even more fascinating question! In a fantasy world similar to medieval times, someone thinks of a perfect spider hole to hide in. A cave under a castle that has food in it enough for years... How do they get air there and yet avoid the possibility of someone noticing a draft?
Unless the bad guy dug the tunnel with his own two hands, how about the good guys getting information from someone in on its original construction or previous use?
There's a lot of things you can do, but you need more information as to what the original purpose of the tunnel or room was when your bad guy was in them in the first place. When the castle was up and running, was it a bunker for the lord or lady, a wine cellar, storage room, sewer system, dungeon, or whatever? If the room is blocked off or hidden, then a dead end to a tunnel under a castle would make me suspicious. If if its a store room, food's gone bad and there could be a lot of mold growing from a suspicious section of bricks. If it's a sewer, then it's blocked up and not working right, thus flooding ensues. Whatever the original purpose is, it's not working right because its likely not supposed to be locked. The consequence to that is your sign that there's something there. Thus an astute member of your group will notice this and find it rather quickly.
