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.
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.
Riario discusses his defeat with the pope and a mysterious prisoner; Leonardo searches for an explanation when the Medicis are blamed for an outbreak of demonic possession at a convent.
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.