The secret key

The sun was lazily breaking through the dense treetops as I ran deeper into the forest. The air smelled of moss and damp earth. My adventure began quite simply -- I was collecting pinecones and looking for animal tracks, but then something flashed among the leaves. I stopped and looked down. There was a key lying among the twigs and mosses. But it was no ordinary key, like the one for the door at home. It was old, decorated with strange patterns and had a carved dragon in its handle. I picked it up gently, as if it might disintegrate in my fingers. I looked around me. What could it fit into? Then I noticed something unusual. Right next to a large oak tree, which I hadn't noticed before, there was a wooden door hiding between the roots. There were no walls or building around them -- they looked as if they led directly into the ground. My heart began to beat faster. Could it be that this key opens this door? I knelt down and slid the key into the lock. It fitted perfectly. With a quiet click, the lock unlocked. I took a deep breath and pressed the handle