Part 09: Between a Rock and a Hard Place - Assassin's Creed: Brotherhood
Completing the Assassins Guild Quest
Out in the eastern countryside on the other side of a tower you cannot approach due to the white wall of death surrounding it, you will find a Villa with an old friend in it. After you speak with him his wife fills you in on what is really happening, and you then flag the quest.
Your objective is to eliminate the Captain of the nearby tower, sending his men to attack the Barracks, so that the Mercenaries can concentrate their force on the French Assault. To gain the 100 % Sync you can kill ONLY the Captain.
Once he is dead jump into the moat and climb up the rear of the tower, go to the top and burn it, then return to your mates Villa and talk to him. When you finish there will be an architect standing nearby -- talk to him and renovate the barracks, then you get a CS with your mate.
You learn about the carrier pigeons from his wife, and then receive 100% Sync for this memory! You have now unlocked the Assassins Guild side of the game, and can start taking contracts if you like. They are all pretty much self-explanatory and you can complete them whenever you like!
Remember if there are any towers you can clear that you have not, you should clear and burn them. If there are any shops you can upgrade, do that, and make sure that you keep the bank account empty mate!
Now head towards the last memory on the map, the Thieves Guild!
-- Double Agent --
When you arrive you meet with an old mate who is the leader of the Thieves Guild -- and he does not like Machiavelli -- in fact he claims that the man is a traitor! You argue on Machiavelli's behalf but word comes that the man is having a secret meeting, and your bud decides that you both need to check that out!
For full Sync on this you cannot be detected throughout, including while lowering notoriety and traveling back to the Guild.
Go to the marker on the map and you will witness what for all the world appears to be a betrayal of trust. Standing on the edge above switch to your gun and shoot all four of the soldiers for the quick and dirty approach! The CS will join you with the boy, simply lead him out of there to he nearest group of courtesans, hire them, and use them as cover to reach the marker.
Your next task is to reduce notoriety by tearing down posters, and then rejoining your mate at the Guild -- without being detected the whole while!
Once you have the notoriety removed head to the guild and chat with your mate, then talk to the architect to upgrade the Guild to make it look like an Inn. If you did everything correctly you should clear this memory with 100% Sync!