The Nightcrawler

Every night, as I'm working away in my office, I'll hear this soft moaning sound coming from the hallway. It might not seem like much, but at 10pm in a house/office that is humongous, it can be quite frightening. I went out into the corridor once to see what was making the noise, and I saw some wild cat standing in there, making that odd sound. The cat must crawl into the office from one of the windows that is left open. Let me tell you, it is a scary thing. I was sleeping once when I heard the moaning noise, but I was so scared, I just slid further under the covers and covered my ears until the moaning noise stopped. Who knows what kind of disease/wild fighting skills this cat might have, so that prevents me from getting too close to it. And what kind of cat makes moaning noises? Granted, there are some strange animals here. People interbreed dogs, and they turn out crazy and hyper. I even saw a dog with something like 10 teeters. No joke.