Zael and Yurick make their way to a cave and they find a shipwreck. It looks like it's been there for a while.
They enter the ship, and it goes to Zael's first person view. Look down to the right to see the ship has taken water. Yurick will then jump in and go to the next area, with Zael following after him.
Once in the first area, follow Yurick to the doorway. Examining the door leads to Zael almost getting hid in the face with a sandbag trap. Move on to the next room. The footing here is very unsteady, and something comes out from the water. Two giant crabs come out to attack Zael and Yurick. Both crabs can cause Poison, so be careful as you don't have Mirania or Calista with you to heal. Once you've depleted the crabs' HP (they fall on their backs) you need to Ride them to finish them off.
Continue on. Before following after Yurick, head back and towards the right of the entrance Zael came from to find a chest there. Then head to the left corner over a floating crate for another chest. Follow after Yurick and open the door to a dusty hallway. A brief scene occurs, as Yurick nearly succumbs to poison from the crabs.
Zael realizes that somewhere on the ship is an Antidote, he leaves Yurick in the hallway and goes looking for it. Climb up the ladder to the next area. Zael can explore this area to find the Antidote for Yurick. But first, head upstairs on the right and go down the hallway to find a chest. Leave and go downstairs to the large room for another two chests. Return to the room with the ladder and you'll see a chest to the left of it, this was where the Antidote was all along. Take this back to Yurick.
With Yurick back on his feet, head up the ladder again to continue exploring the ship. Approach the curtain for another scene. Dagran and Mirania join up with you.
From here, Zael can go either downstairs (left) or upstairs (right). It doesn't really matter which one if you've already taken the treasure earlier. Both routes just have different monsters to fight. Mirania will go with Dagran and Yurick stays with Zael.
Downstairs, another crab attacks them. Open the doorway to find a group of Undead.
Upstairs, it is more or less the same.
Deal with them and head upstairs/downstairs. They reunite with Dagran and Mirania, who are fighting off a large group of crabs and undead archers. Use Yurick's magic to take down the archers.
There is a scene afterward, and Yurick lowers a ladder to the next area. The party then can climb up a ladder to the next area. Before doing so, check to the area left of the ship's wheel next to a fallen pillar for a chest. Climb up the ladder to the next level of the ship.
Go inside the next room. Indeed there is a table full of food. Move past the table and examine the mirror.
The wall moves away from the party, revealing a hidden door, which Yurick dashes into.
Chase after Yurick, but first immediately in the right of the hallway is a chest. Continue down the hall and into a room with a save point. Save then enter the next room for a scene, approach the red curtain for a boss battle.
Boss: Doppel Ganger
Just as it looks, it's a doppelganger. If Zael attacks it with his sword, it will block, then counter.
Dagran will immediately notices that magic circles go past the mirror.
The doppelganger will shoot sticky goo at the party, so your best bet is to actually attack it upfront. Once it strikes back at Zael, it will laugh at him, and that's your chance to strike it while the 'reflection' is no longer copying Zael. Deal enough damage to it, and the doppelganger gets upset and breaks through the mirror.
Once out of the mirror, it jumps onto Zael's head and starts clawing at him. Shake the control stick to get rid of him.
Unfortunately as you did that, he then copies the rest of the party, Zael included.
At first you don't know which one of the copies of your friends is the real one yet, so take out the fake Zael first.
Yurick will point out that the fakes have a black and red light on them, around their eyes.
If you hit one of your friends, they WILL complain/berate/swear at you, letting Zael know that you're doing it wrong.
As you take out each of the four doppelgangers one by one, they will begin cycling through party members to confuse you.
When one of the people have a ? mark over their heads, its likely to be one of your friends and NOT the doppelganger.
When they pretend to be Mirania and cast Cure, use Yurick's Reverse Spell to create damage circles and prevent them from healing themselves.
Once taken care of, the Doppel Ganger drops the Fang sword.
Another cut-scene occurs, then the party returns to the ship.