Da Vinci's Demons - S2

Leonardo helps the wounded Lorenzo to escape from the Pazzi, but Lorenzo is dying from loss of blood. With Verrocchio's help, Leonardo creates an improvised blood transfusion, giving his own blood to Lorenzo. While weakened during the transfusion, he has visions. While Lorenzo and Leonardo are incapacitated; so, da Vinci goes over the writings of Ibn al-Nafis to administer blood to Lorenzo. In the meantime, Riario and the Pazzi attempt to take over Florence. Clarice and her children barricade themselves in the Medici palazzo. Zoroaster and Lucrezia attempt to commandeer the Basilisk to find the Book of Leaves, but Riario captures them and takes the ship for himself.

Riario attempts to execute Zoroaster and Lucrezia by making them walk the plank while chained together, but they survive. Riario proceeds on his way to the Americas, while Leonardo attempts to help Lorenzo to regain control of Florence. He rigs up a form of amplifier using bells, so that Lorenzo can be heard in much of the city center. Lorenzo rallies the people to defend the republic and reject the attempt by the Pazzi and Ferante to take over Florence. With Lorenzo back in power, Leonardo says he must leave to find a ship to continue his search for the Book and his mother. Lorenzo gives his blessing, and, to signify their new bond, gives him the smaller of the two Medici longswords, cleverly hidden within the larger one by Cosimo.

Pretending to be Count Riario, Leonardo attempts to take over a ship, but Prince Alfonso of Naples, who knows Riario personally, exposes him. Leonardo and Zoroaster escape, but Alfonso takes the ship, which has a cargo of slaves. Leonardo invents a pedal-powered submarine in order to sneak under the ship unseen, while Amerigo Vespucci joins Alfonso on board. After nearly failing, Leonardo and Zoroaster get on board the ship with Amerigo's help. Lucrezia convinces Mercuri to enter the Castel Sant'Angelo to meet her father: the real Pope Sixtus IV. The false Sixtus seeks to isolate Florence by excommunicating the city.

Crewed by liberated slaves, Leonardo's ship sails west. But the slaves are convinced they will fall off the edge of the world. Leonardo tries to prove to them that the world is round, but when his calculations of how the positions of the stars will shift turn out to be inaccurate, the slaves rebel. Leonardo realizes that his calculations would be corrected if the earth traveled round the sun, rather than the opposite. But it is too late to convince the slaves. In Rome, Lucrezia meets her father and convinces him to make her a partner in his plans. Lorenzo and Piero, meanwhile, are traveling incognito to try and convince Naples to switch sides. Flashbacks reveal how the false Pope replaced his brother, murdering Lucrezia's sister in the process and driving her on to revenge.

Leonardo and his men land on an unknown shore and find the wreckage of the Basilisk there. Amerigo decides to return to the ship to chart the newly discovered land, vowing to Leonardo to stay on the coast for three months. Meanwhile, in Naples, the captured Lorenzo and Piero bribe a guard for a meeting with Lorenzo's former lover, Duchess Ippolita, in the hope of meeting the King Alfonso II of Naples. Back at Florence, the Medici bank associates plot to displace Clarice as the bank's leader with the help of Carlo de' Medici, Cosimo's long-lost bastard son. Leonardo and his crew are captured by locals and are brought to Machu Picchu, where their arrival has been expected by a mysterious priestess, Ima. Back in Florence, Carlo turns the tables on the Bank associates and reinforces Clarice's position; that night, they give in to their attraction.

Leonardo and Riario have to survive a series of grueling tests before they can enter the Vault of Heaven. Leonardo is bitten by a poisoned snake, and Riario must find the antidote while being hunted by warriors. Ima has sex with the feverish Leonardo, who experiences a series of visions while drugged by the poison. In his dreams he sees his masterpiece, the Mona Lisa, and meets himself as an old man, who reveals that the enemy stalking Leonardo and the Sons of Mithras is known as the Labyrinth. Meanwhile in Naples, Lorenzo is also having to face a life-or-death trial. The deranged King Ferrante places Lorenzo on a gibbet with a hangman's rope round his neck. Lorenzo must kill a galloping horse tied to the other end of the rope with a single bow shot. If he fails, he will be hanged. On the road to Constantinople, Lucrezia encounters al-Rahim, who offers advice in the form of the ghost of Lucrezia's long-dead sister, Amelia.

Leonardo successfully solves all three puzzles of the Vault, but is betrayed by Ima, who says he must be sacrificed to save her people. From the vault, he hears his mother's voice. Clarice and Venessa are attacked in Florence, with Carlo narrowly saving the day. Lucrezia Donati, along with her bodyguard, meets with Bayezid II.

Leonardo and Riario are to be sacrificed by Sapa Inca; Zo and Nico are to be enslaved. However, they escape, and Leo takes the key to the vault back from Ima. They enter the vault, but instead of the Book, find a brazen head with Leonardo's mother's voice recorded in it. Using makeshift parachutes, they escape from the vault; Ima is devastated by the absence of the Book of Leaves. Leonardo and the others are picked up by Amerigo. Outside Constantinople, Lucrezia convinces the Sultan's son to visit the Pope in Rome, who promptly rejects his offer of peace and humiliates him. In Naples, Lorenzo is forced to surrender to King Ferrante and The Pope.

Returning to Florence to find it occupied by the Duke of Urbino, Leonardo joins forces with Carlo to free Clarice and liberate the city, but Carlo reveals himself to be an agent of the Labyrinth and kills Verrocchio. Meanwhile, Lucrezia is interrogated by the Sultan's soothsayer, who after learning the truth of Lucrezia's parentage explains that her father wants to start a war between Christendom and the Ottoman Empire. Riario, now wanting to follow the true Pope, asks for absolution, but the real Sixtus angrily rejects him. Later, in Naples, Ferrante is assassinated, thus putting Lorenzo at the Pope's mercy.

Italy prepares itself for an attack from the Ottomans. Riario is been stalked by danger. Nico is the only person who can control what happens to Vanessa.