Al-Sabbah meets the caliph Al-Mustansir Billah, then the scales tip with the killing of the caliph and his son. Al-Sabbah is expelled on a ship bound for Morocco.
Al Sabbah returns to Isfahan and the three friends, Hassan Sabbah, Nezam Al-Mulk, and Omar Khayyam, reunite once again. Will they fulfill the covenant?
Al-Ghazali explains to his students the differences between the sects and shows them the truth about the mystical sect. Sultan Malshkat is preparing to visit the Abbasid Caliph to marry the Sultan's daughter
Hassan's plan to kill the Abbasid Caliph fails. Nourhan runs away on her wedding night and is kidnapped. Hassan is arrested and Abu Ali confronts him that he has betrayed the covenant and threatens to torture him and then kill him.
Hassan seals all castle doors but keeps one hidden, Hassan sends his son to another castle to train. Sutlan Malik-Shah prepares for war against Hasan after the latter kills his jester and threatens him.
Hassan sends his strongest soldiers to fight the army, and the war continues in several directions. Terror and panic spread in the hearts of the king's army.
Hassan takes advantage of the Isfahan power struggle and begins to publicly assassinate anyone who opposes their call. Berkyaruq, the older son of Malik-Shah, assumes the caliphate, and Hasan sends him a threatening letter.
Hassan orders Buzurg to assassinate Mansour after he retracted from assassinating Al-Ghazali and joins him. Omar Khayyam arrives at Alamut. Hasan orders the killing of his son, Husayn, in public
Hasan orders Buzurg to assassinate Mansour after he retracted from assassinating Al-Ghazali and joins him. Mansour tells Al-Ghazali about Hasan's views and methods. Omar Khayyam arrives at Alamut. Hasan orders the killing of his son.
Buzurg kills Mansour. As Berkyaruq besieges the castle, the tribes nearby ostensibly join the Seljuk army so they can help Hasan in wartime. Hasan sends misleading messages to the army that are only understood by his followers.
Donia Zad confronts Hasan with the truth about his religious deception after killing their son. Badr al-Jamali is assassinated for killing Nizar. Berkyaruq orders the lifting of the siege and the return of the army.
After he returns to Isfahan, the Sultan asks Omar to draw a detailed map of Alamut Castle. Zaid recognizes Yahya when he arrives at the castle. Hasan chooses Yahya to enter heaven's dream, in which he sees Nourhan.
Zaid becomes worried from Yahya and Hasan's madness after they confront each other. Omar is imprisoned for refusing to draw the map. Hasan incites Siraj al-Din to spy on the Sultan, while he asks Yahya to write a report about his friends.
Jealousy increases between Buzurg and Zaid. Hasan orders his followers to carry out a number of assassinations and burn a mosque in Baghdad. The attempt by Yahya and his friends to kill Hasan, Buzurg, and Zaid fails.
Zaid and Buzurg kill Yahya's friends, and Hasan asks the latter to dispose of their bodies. Hasan's follower kills the Crusader army's leader for refusing to pay tribute when passing in front of the castle.
Hasan decides to take revenge on Zaid by sending him and Yahya to Ibn Hafez's castle to fight the Seljuk army. Alinar fails to kill Nourhan when the latter escapes and accidentally enters Donia Zad's room.
After Zaid escapes to the castle, Hasan doesn't trust his story of Yahya's actions and imprisons him. Berkyaruq defeats the Batiniyya. Al-Hadi helps Donia Zad and Nourhan flee the castle.
Yahya kills Zaid and orders Yahya to kill either Nourhan or the Abbasid Caliph. Hasan imprisons Al-Hadi for helping Donia Zad and Nourhan escape. Yahya goes to kill the Caliph and Hasan sends his followers after him to assassinate him..
Yahya goes to Isfahan instead of killing the Caliph and asks to be an army commander. Berkyaruq summons Donia Zad and Nourhan to his palace, while Hasan leaves the castle for the first time in years and proposes to a girl.
Hasan marries the shepherd's daughter, hoping to have another child. Yahya marries Nourhan. Donia Zad exposes Hasan in Isfahan after she returns home. After Hasan releases Al-Hadi, he appoints him as his successor.
Buzurg's push to Al-Hadi turns out to be Hasan's nightmare. Hasan's followers in Isfahan cause chaos and murders. The Sultan appoints Siraj al-Din as his vizier, unaware that he is Hasan's spy. Alinar is killed.
Hasan orders the killing of Donia after learning that she is inciting the women of Isfahan against him. Yahya is imprisoned and then executed for killing a Seljuk soldier. Siraj lies to the Sultan and makes him doubt everyone around him.
The Sultan kills Siraj after learning of his manipulation. Al-Hadi writes a book about the biography of Hasan-i Sabbah and it is distributed in several countries. Hasan appoints Buzurg as his successor.
Barzak takes over the affairs of the castle after Hasan grows old and mixes reality with fantasy. Saeed joins the castle and begins secretly killing soldiers in revenge. After Hasan's death, the castle is destroyed by the Mongols.
