A former nemesis returns to Florence and stands in opposition to Crusade efforts; Vanessa and Nico ponder their futures; Leo attempts to decipher the Turkish armor.
Leo and Sophia struggle to control the mysterious device they've built. Back in Florence, Riario awaits judgment while Lorenzo and Vanessa take their partnership to the next level.
Leonardo continues his search for the Book of Leaves; Lorenzo is forced to make sacrifices when Pope Sixtus takes aggressive measures against Florence; Lucrezia looks for new alliances in Rome.
Leonardo attempts to navigate the Atlantic without maps; Lucrezia is smuggled into the Vatican for an important meeting; Lorenzo's identity is discovered during his trip to Naples.
Riario and Nico are reunited with Leonardo in the New World; Lorenzo tries to save Florence with the help of a former flame; Clarice works to retain control of the Medici bank.
Entering the Vault of Heaven presents challenges for Leonardo and Riario; Lorenzo becomes a part of King Ferrante's bloody games; Lucrezia meets the Turk in Constantinople.
The powerful Medicis commission rising artisan Leonardo da Vinci to create an Easter spectacle in Florence; Leonardo takes on another assignment to engineer war machines; the arrival of a mysterious Turk intrigues Leonardo.
Leonardo continues his quest for the Book of Leaves; the pope's nephew arrives; the failure of Leonardo's war designs causes a rift with the Medicis; the pope learns of Leonardo's talents.
Lorenzo orders Piero da Vinci to defend his estranged son in court; Leonardo surprises the corrupt judge during a performance for visiting royalty; the Turk visits Leonardo at his workshop.
The Turk's clue regarding the Book of Leaves leads Leonardo to Wallachia, where he meets Vlad Dracula; Lorenzo and Piero encounter the Duke of Urbino; the hunt for the true spy continues.
Leonardo builds an underwater suit and travels through the sewers to enter the Vatican, where he meets the pope and the mysterious prisoner; Giuliano reveals the identity of Rome's spy.
The Pazzis plot to kill Lorenzo and Giuliano on Easter Sunday; the Turk reveals the location of the Book of Leaves; Lucrezia makes a confession; Leonardo tries to save the Medicis.