The Guard's House is a large building with stables that houses the Captain of the Guard in Mythrad.
The Guard’s House is a typical Mythradian homestead, with wooden walls and a thatched roof. It is larger than most, and has a small stable around the back. The house is owned by Rheshus Haggor, head of the town guard.
If you knock, there is a 25% chance that Rheshus answers.
You may talk to him about Mythrad and anything else you fancy, he seems slightly shifty but not anything to cause too much suspicion.
If you already know he is a traitor, you can question him about it, which will instantly initiate combat.