The History of Byzantium

Pope Innocent calls for a new Crusade to retake Jerusalem. A group of French Knights decide to form an expedition to Egypt and make a deal with Venice to transport them. But when they can't pay the bill the mission goes awry and ends up at Constantinople. 

Alexios Angelos faces down one internal rebellion after another as the Roman Empire continues to contract. The biggest threat to his throne comes from disgruntled aristocrats and the people of Constantinople. 

Isaac Angelos does his best to secure his position and confront the Bulgarians. But he is overthrown by his brother at the head of a coalition of aristocratic families.