The Hermeticist leader Ercole Massimo realized that the Renaissance visionary Leonardo da Vinci had discovered the entrance to a mysterious Temple honoring the ancient Greek scholar Pythagoras beneath Rome. He had his disciples take Leonardo to the depths of the city's catacombs, then beat and torture the inventor to get the answers he sought. Despite the ill treatment, Leonardo refused to share his knowledge with the extremist, aware that any potential discoveries would be misused.
After investigating the disappearance of his friend, the Mentor of the Assassin Brotherhood, Ezio Auditore da Firenze, entered the catacombs and confronted the Hermeticists before cutting down the cultists and assassinating a pleading Ercole.
With Leonardo safe and the threat ended, the duo entered the temple and obtained the cryptic message within.