Assassin's Creed Revelations Part 3 – A Journal Of Some Kind

Talk to the man inside the room to learn what has been happening here. He explains that the Templars have him trapped but he does tell Ezio that the Captain has a kind of Journal that may hold a description of the keys that are needed to open the massive door.

The Full Synch condition for this memory is to not fail a single tail.

Move forward and head up the stairs in front of you. Interact with the glowing door and continue on up the stairs. Head over to the right from the top of the stairs to the next waypoint. If you want, take a moment and head to the left. There you will be able to climb the stairs and find your way back to Al Mualim's study. There are a number of objects that you can play with that have the classic Animus Effects and a chance to look out on the courtyard again where you fought Al Mualim. After all that, then go for the waypoint marker.

Outside you will see a cutscene telling you that the Captain is down in the village. You need to get out of Masyaf and find the man. Just beyond the door, on the left, you will see a patrol of guards. You can either engage them or go over the railing and break to the left to slip up the slope quickly while they head the other way on their patrol.

Climb the ladder and at the top you will find another group of Templars to deal with. These you need to confront. Take a moment after you will them to loot the bodies and collect some good ingredients for bombs. Head to the right and climb upwards from the cloth covered barrels. At the top head for the makeshift stairs and into the last waypoint marker.

Now follow the on-screen prompts to use the Parachute and steer toward your target. You will land behind your target Templar and his entourage. You cannot lock onto him but with the marker it is easy enough to follow him. Keep a fair distance between them and you while staying out of their line of sight. Crossing the village using the rooftops is a simple way to give you the best chance of success.