Assassin's Creed/Memory Block Six

Jerusalem: Middle District

 * Objective: Assassinate Robert de Sable

Investigations

 * 1) Eavesdropping
 * 2) Informer
 * 3) Interrogation
 * 4) Pickpocket

Informer Pickpocket 
 * Console version

Informer Informer 
 * Windows version

Assassination
Your target will be in attendance at the funeral of Majd Addin, who you assassinated the last time you were in Jerusalem. You can sneak in with Scholars, or just hop a far wall and walk into the ceremony. The Templars are ready for you this time, and you'll see de Sable indicating he knows of your presence to his underlings during the cut scene. Suddenly he'll shout that there is an assassin in their midst and the citizens will clear out. You have a couple choices here. You can stay and fight in the cemetery, or run out into the city to get away from the archers and try to take out your target when he's alone. If you stay and fight, consider heading up the ladder, as your enemies can't surround you, and you can use the ladder bottleneck to dispatch the Templars.

Whether you fight in the cemetery or the city, after you finally best the target and find out it was an imposter, you'll need to make your way back to the Bureau to warn someone. Your orders are to report back to Al Mualim in Masyaf, but Altaïr thinks it's more important to stop de Sable from uniting the two warring nations against the Brotherhood. In that case, you're off to a new destination: Arsuf.

Arsuf
When you get to Arsuf, by riding directly from Jerusalem or by warping to a nearer city like Acre first, you'll find that it's a long series of fights with the Saracens and English soldiers down a long path blocked by memory walls. You'll need to dispatch all the enemies before your memory synchronizes enough with Altaïr's to allow you access further into the memory. At times you'll be fighting huge groups of up to ten enemies, so patience and your counterattack skill will be extremely helpful in these fights. If you lose a lot of health, don't be afraid to wait around for your sync bar to replenish before moving on to the next area. Eventually you will fight all the way to Robert de Sable, in conference with King Richard himself.
 * Objective: Warn King Richard of Robert de Sable's plot

After informing the king of the plot against him and the other ruler, Richard will leave the decision of who to believe up to God, meaning whoever wins in a fight between you and de Sable. Before fighting your nemesis however, you'll be attacked by ten Templars. Use the same techniques as in the earlier battles, with just biding your time and using counterattacks to do your killing. It's even more important here to be patient, because you don't want to start fighting de Sable with a low sync bar.
 * Objective: Kill Robert de Sable

When you've dispatched the Templars, Robert de Sable will attack. The easiest way to beat him is to do a counterattack, and then unload all your throwing knives into him. You can't hit him while he's down with melee attacks for some reason, but you can take him out in one go without even exhausting all your knives if you stick to just throwing them. It's a bit anticlimactic, so if you're keen on finishing the fight like a gentleman, you'll need to perform six counterattacks against him instead.

When it's all over, you'll continue your chat with the king before the memory block ends and you're back in Abstergo.

Epilogue
You'll find that a rescue missions has been mounted on your behalf back outside the Animus, but unfortunately your saviors are overwhelmed by the Abstergo forces. Talk to Lucy after Dr. Vidic leaves, then head back to you bedroom. When you come out this time, you'll find the keycode to the conference center in Lucy's emails. In there you'll be able to access another computer with some more email to peruse. When you're done, go back to bed and wait for Vidic to wake you up for the final trip into the Animus.