Retaking of Masyaf

"Impossible! The student does not defeat the teacher!"

- Al Mualim at Altaïr's feet

After killing Robert de Sable, Altaïr Ibn-La'Ahad rode for Masyaf to confront his master, Al Mualim. Upon entering Masyaf, a man greets Altaïr. Altaïr asked where everyone was and if it was the work of Templars. The man spoke in cryptic words regarding finally seeing the truth and light, and that the master was responsible for this enlightenment.

From this, Altaïr knew it was the doing of Al Mualim, and headed toward the Assassin's Fortress to liberate the village.

The Mindless March
On the way to the Fortress, Altaïr saw some of the Assassins blocking his path. Upon seeing Altaïr, they drew their swords. Altaïr attempted to fight them off, but there were too many. Before Altaïr was overwhelmed, Malik A-Sayf and some of the other Assassins who were not yet controlled by the Piece of Eden drove them off and saved their brother.

Altaïr ran up to the top of the hill to meet with Malik and the others. Altaïr told Malik that Al Mualim had betrayed them; Malik agreed to this and added that the Master had betrayed his Templar allies as well. He explained that after they had spoken, he had returned to Solomon's Temple and found Robert's journal filled with revelations regarding the Apple's use to control the Holy Land. Altaïr then advised Malik to lead his men to distract the thralls in front of the fortress long enough for him to reach Al Mualim.

Altaïr and Malik went their separate ways, with Altaïr heading into the Assassin's Fortress courtyard. Standing in front of the Fortress doors was a large group of Al Mualim's mind slaves. Careful not to hurt them, Altaïr made his way through the crowd and into the Fortress.

The Duel
Altaïr saw the door to the Assassin's Garden open, and decided to see if Al Mualim was outside. As he stepped through, the door shut behind him, and he became immobilized by the spell of Al Mualim's Piece of Eden. After a brief taunt, Al Mualim used the Piece of Eden to disguise some of his Assassins as Altaïr's slain targets, and commanded them to destroy Altaïr. However, Altaïr managed to pick them off one by one. Al Mualim then used the Piece of Eden to clone himself, but Altaïr used his Eagle Vision to see past the illusions, and strike the real Al Mualim with his blade, making the clones disappear.

Al Mualim decided to have a proper duel with Altaïr, but not before having a final talk with his protégé. Altaïr yelled that Al Mualim was worse than Robert, and that people would resist his plan; to which the old man replied that there would never be peace so long as men retained free will. When Altaïr snarled that he had killed the last man to speak as such, Al Mualim sneered that his threats were just empty words, to which Altaïr retorted that they were words he would put into action. When Altaïr asked why his master never used the Piece of Eden to enslave his mind like the other Assassins', Al Mualim answered "Who you are and what you do are twined too tight together. To rob you of one would deprive me of the other, and those Templars had to die!" However, he then reveals that he did try but was unsuccessful, due to Altaïr's seemingly natural resistance to the illusions conjured by the Piece of Eden. Al Mualim went on to explain that every strange and mythical event he had attributed to the treasure - Jesus turning water to wine, the parting of the Red Sea, the influence of the Greek Gods in starting the Trojan War - were all illusions created by it.

Altaïr retorted that the Templars' plan to create a "New World" using the Piece's power was just as much an illusion as the others; but Al Mualim replied that it was no worse than the world around them, where the Saracens and Crusaders slaughtered each other in the name of non-existent phantoms. As he put it, "They live amongst an illusion already. I'm simply giving them another, one that demands less blood!" Al Mualim remarked that they had come to an impasse; he would not yield in his plan, Altaïr would not join him willingly and he could not compel the Assassin to follow him. Ending the Piece of Eden's hold, Al Mualim drew his sword, and he and Altaïr engaged in a final duel to the death. It was a long and hard-fought battle, but eventually Altaïr triumphed, and dealt his master a fatal blow.

Aftermath
As Al Mualim collapsed to the floor, dying in Altaïr's arms, he was surprised by the realization of his loss. "Impossible. The student does not defeat the teacher!" he said, to which Altaïr replied "Nothing is true, Everything is permitted." As the Piece of Eden rolled out of the master's hands, Altaïr remarked that the old man had been playing with fire by trying to use it, and should have instead simply destroyed it.

The dying Assassin replies that it is the only means of creating true peace in the world, and that he could never destroy such a thing. Altaïr claimed that he would, but as he approached the Piece of Eden, he became mesmerized by it. Al Mualim challenged him to destroy the artifact as he said he would; Altaïr replied that he was unable to, to which Al Mualim sneered with his last breath that he could, but he wouldn't. A hologram of the entire world and the locations of all the vaults projected from the ancient artifact, and at this moment, Malik and his men arrived to join Altaïr in the fascination of the artifact.