In the end of the previous chapter you were on your way to Syria to warn Chloe and Cutter that they could have been followed. It is now night time, and you are standing in front of a Citadel.
The chain on the door has been cut. Open the door. Your plan is to sneak in, rescue Cutter and Chloe, and sneak back out.
Reach the gate with the blue Arabic sign on it. It is locked. Climb to the left and around it. Reach a big door. Ask Sully to help you open it but you dont know whats on the other side so better check it out first. Climb around to the right and then back on the wall. Get to the top. You'll see Marlowe's men in the courtyard inside. Shoot them from above the wall. Shoot propane tanks in their area for massive damage. If they throw grenades at you, make sure to throw it back on them.
Once you have defeated them all, open the door from the inside to let Sully in. Tap triangle to turn the wheel and lower the drawbridge. Cross the bridge and get to a locked gate, shoot the lock and go in. Reach another locked gate, this time its locked from the inside. Go to the well on the right and hang on the basket. Have Sully lower you down. Check out the tunnels below. There will be more of Marlowe's men down there. Climb up the wall at the end of the tunnels and shoot the lock.
Go through an arch and there will be a cutscene. You will run into Cutter and Chloe. They have discovered that not only did Elizabeth's Spy Network stretch over here, but they were all part of some Hermetic secret society. The British Occult Secret Service, The School of Night, The Hellfire Club, The order of the Golden Dawn - theyre all connected. Marlowe and the crew are the same secret order. The key to all of this is "As Above so Below". You need to get to the highest point of the castle. You should be able to find your way into the crypts with this clue. The entrance needs to be hidden here someplace. You have to reach the highest tower. But there are thugs in the middle.
Get above the thugs, jump and knock out one of them silently, then get the others from behind.
At this point more guards will join in, some with laser pointers. Kill all of them. Head to the entrance in the base of the tower and climb the stairs. Open the gate. Head up the spiral stairs. Kill enemies on the way.
Some enemies will be armored so watch out.
An explosion will cause you to fall down the tower. Hang on to the chains, then climb the rock platforms to get back to the top. Use chains to get to the window and go through it. Shoot the enemies inside and keep fighting your way through the tower. Open the door and get into a fistfight with a brute. Climb the spiraling stairs to the top of the tower. find the symbol. The crusaders wouldve hidden the entrance to the crypt somewhere in plain sight. You will have to follow the direction of the north star back to the castle to get you to the crypt's hidden entrance. Sully will give you binoculars, use the scope to find the star. Entrance will be right below it.
The enemies will shoot a missile at you. Make a run for it. Click the Right stick while aiming to zoom in on enemies and snipe them. There's a wire which you can use to zipline across, but not while they are firing at you. Kill all of them then zip across the wire. A missile will hit and you and cutter will be thrown down. Run on the ledge of the walls to reach the other side. You have to find a way around to meet up with Sully and Chloe. But you are near the tower entrance so you want to check it out. Enter the entrance, try to kill the guard there stealthily. Climb the stairs, then get rid of the other guard thats patrolling the top. Use automatic fire and grenades. There will be a major battle in the courtyard, lots of enemies many of them with protective gear on them. Defeat them all and pick up the Raffica Pistol.
Go up the stairs. Open the big door and find a storage room. Notice the statues on the side. One hand up, one hand down. Use the scope again. See the symbol on the floor. Then move the scope upward. See the pillars. Meet up with Sully and Chloe on the way. You can't stay pinned down there, you have to move. Again you will be attacked by lots of enemies with body armor and laser pointers. Kill them as you make your way through. Use cover to your advantage by hiding behind walls and doors. Shoot propane tanks for some quick kills. Stay out of the lasers. You can get to the pillars from the nearby tower. Climb the two sets of stairs then climb the walls. Meet with Cutter and Chloe. Climb down and reach the wall . The crypt entrance should be here someplace. Two pillars are used to mark a gateway. Use green triangle button to survey the walls. There will be a cutscene. Cutter will be ambushed by Talbot who shoots some sort of dart at his neck. The dart appears to have some hypnotic effects on Charlie, as he is not able to shoot Talbot and instead surrenders him his gun and the Journal. As Talbot leaves he whispers to Cutter not to trust Drake. Cutter is pretty shaken up us Talbot leaves and is still under the influence of whatever poison was in the dart.
Keep looking for the crypt entrance. Chloe realizes that they have got it all wrong. It isn't the space between the pillars, it's the middle pillar. Push the middle pillar. Go inside.