Assassin's Creed 2 Episode 6: Fox Hunt

"After their victory at San Gimignano over Vieri de' Pazzi, Ezio Auditore, Mario Auditore, and his mercenaries returned to Monteriggioni."
"Ezio Auditore returned to Florence after two years. He traveled to Leonardo da Vinci's workshop to have the codex page he took from Vieri de' Pazzi deciphered. While there, he asked Leonardo how he could obtain information on Francesco de' Pazzi."
"As informed by Leonardo, Ezio searched for the mysterious person only known as "La Volpe" within the markets of Florence."