After venturing underground, Nate returned outside and began his search for the treasure vault. After shooting down several mercenaries, Nate found himself going in circles until Sully informed him about a secret gallery at the top of the church. Nate proceeded to make his way over there.
After some serious climbing, Nate ended up at the top of the sanctuary and had to traverse many platforms, plus activate two key switches to find the gallery. He opened a window bearing the symbol used by the Spanish to mark their treasure vaults (two crossed keys passing through a heart). From the window, he was given a clear view of the graveyard behind the church, and a mausoleum marked with the same symbol. Unfortunately, it was the same mausoleum that Sully had previously sent Roman and Navarro to on a red herring.
Passage to the VaultEdit
After informing Sully of the situation, Nate climbed down the outer wall of the church, while Sully created a distraction to get Roman and Navarro out of the mausoleum. After getting past the goons scattered about the graveyard, Nate met up with Elena and Sully in the mausoleum, where he once again had to solve another puzzle by referring to Francis Drake's diary. Successful, he opened up a secret passageway that led into the treasure vault. Nate and Elena began to enter, initially thinking it was a dead-end, until Elena stepped on what happened to be a secret switch that caused the door to close back up, forcing Sully to stay behind and Nate and Elena to explore themselves.
Search for the galleryEdit
There is no apparent way out of this area, as you have on your left a blocked gate, and on the right a set of stairs leading to a locked door. Head for the dead-end on the left path, where you can use the stone graves to reach a handhold on the wall. Shimmy along with it, using other handholds and vines until you reach the other end. Here, climb to the top to reach a broken window, then drop down and return to the second floor of the first building initially visited with Elena in "Sanctuary?".
Prepare for a short firefight, as several mercenaries rush in to confront you, as soon as you drop to the ground. It can be helpful to shoot them down by hanging from the ledge. Once they are all down, leap across several gaps until you reach a room, where you must pull off a small bit of platforming to reach the small stairs on the other side. Proceed along the path until you come across a gaping hole, through which you will spot a vine that hangs down. This vine will lead you up to a window, and you will find yourself at the top of the church interior that you visited in "Going Underground". Shoot down the two mercenaries that confront you here.
After killing the enemies, approach the only wooden planks jutting out from the stone platform, as doing so triggers a short cutaway to the window at the other end of the room, indicating that it is where you need to go. From the second set of planks, jump to the outcrop on the wall, then to the next pillar, watching for the crumbling handholds, and from there to the third set of planks. From here, you can reach the first chandelier, followed by another pair of wooden platforms. After the second, you must jump onto a pillar, and from there, jump backwards onto another set of planks, which leads to another set. From here, you must reach both keys located on walls on either side of the window.
Start with the easier rightmost key, which is accessed by jumping to the chandelier and then a large wooden walkway. Jump and hang onto the key to lower it, then return to the chandelier. Repeat the same action on the other side of the church, but instead you will be crossing a series of handholds on the walls to climb to the walkway. Watch for the gaps in the floor, and after lowering the key, climb onto the pillar next to it (note that you can do the same at the other key instead as well). From here, shimmy around it, then use the hanging chain to swing yourself to another handhold, which allows you to reach the tipped over window and enter the secret gallery.
Approach the one odd window with the heart design to trigger another cutscene. Afterwards, drop down and shimmy around. When you reach the vine leading down, Roman and Navarro will leave their position, after which you can slide down to the ground.
The mercenaries will not initially spot you, giving you time to grab the nearby Dragon Sniper. The mercenaries will have their own Desert-5-wielding snipers stationed on the far left, atop the staircase, and the far-right, atop a mausoleum. Also, keep a close eye out for the one using an M79, positioned near the center of the fence. The others consist of three mercenaries with 92FS-9mms and one with a SAS-12, who will not appear until the fight starts. You should also be mindful that at least one or two of the mercenaries will most likely flank you and walk up the stairs, which can be dangerous if you are busy aiming the Dragon Sniper.
Once they are all dead, procure any ammo you may need, and head towards the left set of stairs. At the top, another group will start attacking, starting from the other end of the cemetery to your right, near the mausoleum. These will all be using M4 rifles and SAS-12 shotguns. After taking them down, enter the mausoleum.
To advance, you will have a little puzzle to solve here in the room. Examine the symbols you see in the room and compare them to what you see in the diary. You only have to turn the shell, the snake, and the arrows. Rotate the shell and arrows twice, and turn the snake so it faces left, all according to what is depicted in the diary. Once done correctly, a passage leading into the vault will open up, triggering a cutscene leading to the next chapter "The Treasure Vault".