The Bulgarian tsar Kaloyan manages to capture Constantinople. This happens in 1205, after his defeat of the Latin Emperor Baldwin at Adrianople. Kaloyan did not originally plan to attack the city, but is persuaded to do so by some dissatisfied Greeks. The city is delivered to him by treachery. How do the other powers respond? The Venetians, Eporite and Nicean Greeks? The western reaction? Is another crusade launched? Can the Bulgars hold Constantinople?