This side of the story will likely take place right after the events of AC Bloodlines for the PSP. For those who haven't played it, Bloodlines took place mostly in Cyprus, where the successor of Robert De Sable, Armand Bouchart, appeared to be shipping various goods and artifacts into an archive. It turns out, however, that Bouchart was shipping things out of Cyprus rather than in. What is likely going to happen in Revelations is that Altair followed the ships Bouchart (now dead) sent out into Constantinople.

There, Altair will face figures such as Philip of Swabia, Boniface of Montferrat and particularly, the Doge of Venezia at the time, Enrico Dandolo. Dandolo was infamous for his role in the Fourth Crusade which he, at age ninety and blind, redirected against the Byzantine Empire from reconquering the Holy Land, sacking Constantinople in the process. One can guess why he ransacked Constantinople (POE anyone?).

Click here to know more about what happened at the time and more about Enrico Dandolo and his involvement in the Fourth Crusade. Things to be noted is that Venice, and therefore Dandolo, played a major role in financing the Fourth Crusade. Needless to say it's a given therefore that he's involved with the Templars if not one himself. Dandolo agreed to go along with the crusade leaders' plan to place Alexius Angelus on the throne of the Byzantine Empire in return for Byzantine support of the crusade. This ultimately led to the conquest and sack of Constantinople on April 13, 1204, an event at which Dandolo was present and in which he played a directing role. The Catholic Crusaders then took permanent control of the Eastern Orthodox capital of Constantinople and established a Catholic state. He was also involved in the expedition against the Bulgarians, but died in 1205 and buried in Hagia Sophia, where another POE is most likely hidden, if it isn't another of the temples themselves.

Shortly after Cesare was defeated in Viana, the good Sultan, ruler of Constantinople Bayezid II, was dethroned by his son, Selim I. Selim put his brothers and nephews to death upon his accession in order to eliminate potential pretenders to the throne. Very similar to Cesare when you think about it. Selim was also instrumental in expanding the Ottoman Empire's territory, establishing his rule in Egypt and a strong naval presence in the Red Sea, and later destroyed the Mamluk Sultanate first at the Battle of Marj Dabiq and then at the Battle of Ridanieh, which led to the annexation of Syria, Palestine and Egypt. According to some historians, Selim died of poisoning, so one can guess how Ezio is involved in this.

One other thing to note is that Selim's successor was Suleiman the Magnificent, and he was known as Turkey's greatest sultan. Similarly to the way the assassins placed Agostino Barbarigo as Doge of Venice in AC2, I'm willing to bet they did the same thing here, considering how vast the Ottoman Empire had become at the time, it held quite a huge chunk of the modern world (from Ezio's pov). It has indeed been confirmed that Suleiman is allied with the Assassins.

The game begins sometime after the events in The Da Vinci Disappearance, where Ezio questions his life as an Assassin, wondering how it would have been if he had never been one. He thus sets out on a pilgrimage to his ancestor's homeland of Masyaf, which he discovers has been overrun by the Templars. There, he discovers an ancient artifact, which is locked away, and can only be opened with five seals.

The search for these seals takes him to Constantinople, where he finds out that there is an army of Templars, likely led by Selim I, forming in the city - threatening to destabilize the region. Selim I is likely to be after the artifact hidden beneath Masyaf as well, which would explain the Templar presence in Constantinople. Ezio must follow in the footsteps of Altaïr, which will lead him to discovery and revelation. Ezio will be searching for the seals containing Altaïr's memories, through which he will relive his ancestor's memories just like Desmond is going through Ezio's memories. An Animus within the Animus, if you will.