To access this optional chapter, search for Horace on the Arganan bridge once Zael is able to leave Castle Arganan. Talk to him and agree to help him find his wife at the Haunted Mansion.
Zael, Dagran, Lowell, Yurick and Horace will join you. Because Horace is there, you can upgrade your equipment whenever. Just talk to him.
Check the door. It will be locked. Horace will open it. The party is now trapped in the mansion.
Look up at the Chandelier in order to save Yurick from getting hit. Wander around the room for a bit. Dagran will get abducted by 'something'. Open the door, bats come out of the room.
Yurick starts to freak out. Look towards the mirror in the left-corner. Lowell gets abducted as well.
Use Seek on the mirror. Run to the back left corner of the room and Check the book there. Then go back and check the mirror.
Attack the skeleton that abducted Lowell. Open the door to the next room. Yurick will yell at Horace, demanding an explanation about the haunted house. Continue further along the hallway, bats break through the window, and then Yurick will get dragged into the floor, leaving Zael and Horace by themselves. Enter the bed room. Before you can do anything, skeletons attack. Horace gets abducted next by the skeleton during a cutscene. Seek the book in the corner of the room on the nightstand. Check it out.
Check the mirror, then continue to the next room. Immediately look to the right at the sword and shield on the wall. Zael will dodge it. Check the sword (now stuck in the wall) for a Phantom Sword (cursed). Continue down the hall until a door opens for you. Go outside to the grave area. You will notice the gravestones will read the names of the party members, Horace and Horace's wife Meredith. Open up the coffins to find your party members (and some skeletons). Your party members each have a different reaction from being stuck inside the coffins.
Once everyone has been freed, there is another scene involving Zael finding Meredith's glasses. Try to leave the area, then an old 'friend' appears.
Fight Ghoul. Because you don't have higher ground to Slash at him and no walls for Ghoul to get stuck in, use Zael's Dunk Slash ability to deal heavy damage to Ghoul.
Hiding behind the gravestones and using Slash will still cause him to bounce around like a pinball, but because the battle area is small, there is a higher chance of Ghoul hitting Zael and the party during his rebounds.
Once Ghoul has been defeated, go back into the mansion. Zael will see a ghost child. Follow him to the next room.
In Seek mode look at the bookshelf and the party will hear some moaning. Next, Seek under the candle on the right to find a keyhole.
Go out the door that leads outside to find yet another Ghoul and some skeletons.
Sub-Boss: Ghoul and Skeletons
Note that if any of the party members get downed, a black skeleton will come and drag them into the mirror (and back to the coffins where the first ghoul was).
Use the same strategies as before in order to defeat the second Ghoul.
Defeat the enemies and go back outside to rescue anyone who was dragged into the mirror.
However the coffins have closed up again, and now are trapped. It is completely random as to which one your party members are stuck in.
Continue back outside and open the door back into the mansion. Be careful of the bats, they will drain Zael's HP very quickly.
Seek the book in the left corner of the room. Check it to read it. Open the door, and you will be back at the main entrance.
Search the remains of the chandelier for the key. Be ready for another battle after Zael picks it up.
In order to defeat the Phantom Armor, go up to the ones that aren't possessed yet and use the Attack command to break them.
A dark sphere of light will try to possess the armors that you aren't fighting yet. This will make the fight a lot quicker.
Return to the room with the keyhole, through a new door that the party can access. When you return to that room, bats will drain Zael's HP again. Use the white cannon shell to heal him if needed.
Use the key and Zael will fail. He'll call Horace and the door will open. Another cut-scene where Horace will find his wife tied to something.
In order to damage the Vampire, shoot it with Silver Arrows. The ghost child will continue to give arrows to Zael if he runs out.
Once the vampire has been hit by a silver arrow, the party is able to damage it. Chase Nebirous if he runs away.
Nebirous will drop the Death (cursed) weapon after being defeated.
After defeating Nebirous, Yurick will be overjoyed that he can finally leave the 'people-eating' mansion.
There will be a cut-scene and the party will leave the mansion after saving Meredith.
The party returns to the Tavern. Go downstairs to talk to Horace and Meredith. Horace will ask Zael to go visit at his store.
Afterward, continue on to Chapter 24 by going to Horace's store and talking to him. Horace will ask Zael to go recover a book that he lost in a well on the East side of town. The well in question will show up as a red dot on the map, just West of the Marshe.