Lorenzo orders Piero da Vinci to defend his estranged son in court. During a performance for visiting royalty, Leonardo surprises the corrupt judge. Back at his workshop, Leonardo is surprised by the Turk.

Leonardo builds an underwater suit and uses the sewers to enter the Vatican, where he meets the Pope and the mysterious prisoner. Giuliano reveals the true identity of Rome's spy.

The Pazzis prepare a murderous plot for Easter Sunday. The Turk tells Leonardo where to find the Book of Leaves. Lucrezia makes a confession as Leonardo attempts to save the Medicis.