If you managed to make it to the treasury without killing anyone from the moment you were marooned until now you’ll obtain the Trophy: Peaceful Resolution .
Examine the painting on the floor to the left and then crawl under the overturned bookcase to find an Emerald Flask .
There are numerous chests, cabinets, and drawers that you can examine around the room. There are three Journal Notes that you can gain: two by examining four cabinets/drawers and a third for examining two chests. While doing this you’ll want to make your way to the back of the area and examine the impaled corpse to trigger an Optional Conversation with Sam.
Make sure to examine the head of the Avery statue for a Journal Entry and then find Sam to trigger another Optional Conversation , that isn’t that optional.
After the cutscene, push the bookcase to reveal a crank that lowers a chandelier and then climb the bookcase nearby. Grapple the chandelier and swing to the chain hanging from the ceiling and then jump to the paintings. Shimmy left along the paintings and climb up and enter the tower through a nearby window.
Head up the stairs and climb the wall and then turn around and press L3 to spot a grappling point. Grapple the statue and rappel up to swing to the bars over the window and then climb up, boosting Sam upstairs. Use the crate that Sam pushes down for you to reach the rooftop and then follow Sam down the side of the dome.
As you drop down from the dome to the side of the tower Nadine’s men will attack. Continue to drop down to the metal bars below and then hop right to enter the window when it explodes. Climb up and jump across to the glass door and then jump down to Sam and follow him for a quick scene.
When the building begins to crumble and fall you’ll need to grapple the beams above and then pull yourself up the roof. Follow Sam and rush to the doorway, busting it open, and then examine the door on the left, rolling back when the grenade is thrown.
Make sure to jump at the bottom of the mud slide to some more stone ledges and then shimmy around the building. When Nate falls, swing to the beams on the inside of the building and climb up and then use the window to climb up the outside of the building and up to the next floor.
You’ll encounter Nadine once more in a fist fight, but this time you have Sam on your side. Attack until Nadine pins you and then press Triangle to break free and then rush to Sam’s aid.
After being thrown out the window, again, climb the outside of the building and swing to the upstairs floor. From here you can jump down and perform a vertical takedown to complete the chapter.