Before Manuel I could reach Constantinople, his sister Maria realised that her husband, the kaisar Ioannes Rogerios Dalassenos, was trying to usurp the throne. He was making plans with Robert, prince of Capua, who had been driven out of Southern Italy by Roger II of Sicily, and was in Constantinople with many adherents. Maria tried to stop them but failed, so she told ManuelÂ's agents, who lured Ioannes to a suburban estate and detained him