Alexius Comnenus (Isaac II's son) asks for help deposing Alexius III, claims he's bad, & will pay Crusaders debts in exchange. Innocen III says don't do it, they say, screw it & go. People of Constantinople fight crusaders b/c they like Alexius III. Isaac II hears & gives empire to Alexius IV.
One day crusaders set mosque on fire, it spreads to city. Aleixus IV asks general for help, general tricks him, throws him in prison, & declares himself emperor. Innocent III says figure out your own shit.