Assassin's Creed 2 Episode 14: Necessity, Mother of Invention

"Following the death of Emilio Barbarigo, Ezio Auditore traveled to the Santo Stefano, where he caught sight of two Templar conspirators, Carlo Grimaldi and Silvio Barbarigo, on which he decided to tail them."
"After learning of the Templars' plan to kill the Doge of Venice, Ezio Auditore headed to inform Antonio de Magianis of his discovery."