Humanity's last safe city has fallen to an overwhelming invasion force, led by Ghaul, the imposing commander of the brutal Red Legion. He has stripped the city's Guardians of their power, and forced the survivors to flee.
The Ruby Throne lies empty. In the wake of this, unlikely and fragile alliances are made between races as they fight to control the throne. In the midst of this a much more dangerous threat emerges that threatens to engulf all of Tamriel.
Ezio travels to Constantinople, at the peak of the Ottoman Empire to discover the truth behind his Ancestor, Altair, which will help him retrieve a powerful weapon hidden within Masyaf, the ancient assassins' fortress.