"Into the Manse" achievement looks considerably simpler than it is. One might think, at first glance, that one must simply enter a building. While that is partially true, the means to enter that building are not so simple.
Access to the interior of that manse comes near the end of a line of side quests.
It's a romance quest line, and it will include the idea that your Arisen makes out with a young duchess. The game doesn't care what gender the Arisen is... the quest and cut scenes will still include the suggestion of "sleeping together." (Offering this warning, in hopes that nobody would be overly shocked if they aren't into the type of pairing which results.)
Recommended: bring a few skeleton keys with you, when you go to meet
anyone at the Duke's Desmene at night. Two keys are needed for you to escape the dungeon, where the guards will take you, if they see you anywhere within the Desmene after dark.
The set of side-quests needed to enter the manse can be unlocked only during the very first time an Arisen enters the Duke's Desmene.
There is a brief cut scene, just after one leaves the palace (but before one leaves the desmene through its main gate). Pay attention to this cut scene, which points one's attention to a side garden where a petite female in fine clothing is kneeling.
Go talk to her. This will unlock the quest line needed to enter that manse. If you leave the Desmene without speaking to her, you won't get into the manse during that play-through. Her questline only unlocks if you speak with her at that time.
After speaking to her, when next you enter the Duke's Desmene, her maid is waiting between the palace entrance and the audience hall. Speak with the maid. She will request a night-time meeting.
So your Arisen meets with the maid some night. The maid says that her mistress wishes to meet with you after dark. Since it is already dark, you may attempt to go visit the Duchess immediately.
Be aware that the guards will arrest your Arisen if they see 'em there after dark. So either avoid the guards, or else return during daylight hours and hide until dark.
If you choose to arrive during daylight and wait, climb the stairs which lead to the Duchess' chamber. At the top of those stairs, before going out onto the walkway which leads to her chambers, there is a ladder. Climb it, and there is a place where your Arisen can avoid detection until after dark.
Go meet the Duchess at night. Cut scenes follow, indicating the beginning of a tender moment interrupted by her husband (the Duke). Your Arisen is sent into hiding, and the Duchess speaks with her husband until he begins throttling her.
You have the option of waiting silently until he has killed her, or else attempting to interrupt him. To enter the manse, you need to interrupt him.
The duchess will denounce you, and call for the guards. She later brings keys and apologizes, claiming she feared the Duke would kill her if she didn't turn on you.
Use skeleton keys to escape through a tunnel in a different cell which leads to the city's slums.
Play the game, as normal, until "Reward and Responsibility" is finished, and you have received "Deny Salvation."
Do not ferrystone out of the castle, at least not yet. Walk to the front steps, where you will find the duchess' maid again. She will urge you to rescue the duchess, who is being held captive in a manse to the north.
Yes, you guessed it. She is speaking of the very same manse which needs to be entered for the "Into the Manse" achievement.
The maid gives you a guard's uniform to use as a disguise. This disguise is needed to get past the guards who watch the entrance.
Your Arisen can
finally go into the manse, and get the achievement. Do so immediately, since the "Duchess in Distress" quest will automatically fail if you complete "Deny Salvation" before attempting to rescue the duchess.
While your Arisen is in the manse, s/he may as well rescue the duchess (this contributes toward the "hero" achievement, which requires that all side quests be completed).
Rescuing the duchess will complete her quest series. After completing her quests once, one never needs to speak with the duchess again (unless one wishes to do so).
Happy gaming!
