Royal Bed
Once you buy and enter the castle, talk to the butler to show you all the rooms. Sleep in Lord Lucien's royal bed to start this new quest. After you awake, outside the bedroom is a group of bandits. They are easy to destroy with pistols or rifles. Go down the spiral staircase to the throne room, where there are more bandits. Kill them to get to the leader in the library.
Leader
The butler surrenders, and your player enters the Fairfax Tomb within the library. Destroy the bandits using your swords or fire power. The bandit leader is not the large man in the cape, but he is the one on the stairs. Kill him and the rest of the bandits, who are not that difficult to destroy using basic weaponry. Pull the lever on the right, not the left, to open the gate. Down the last set of stairs is a chest with 1,500 gold coins.
Dive
Dive down onto a lower level to kill the rest of the castle bandits. In this new area, there are two more hidden chests with gold. To leave the area, stand adjacent to the door behind the pillar. Shoot the switch twice and then hit it with your sword to open the door. Send a spell the the next door's switch and shoot it when it turns yellow to open it.
Sphere
Investigate the next room to find a sphere or orb. Use a spell on it and shoot it with your pistol or rifle three times. It will give you an elixir to change your sex permanently, if you want. If you do not do this, nothing bad happens. Once you leave the room, the elixir disappears. When your castle is bandit-free, you receive 10,000 renown.