Pilgrims travel to Rome for the Jubilee year celebrations; Catherina wants to hinder the festival; Mattai's contacts destroy a Turkish fleet; Lucrezia sees a change in Frederigo; Micheletto learns his lover is a spy.

Alexander and Cesare have reconciled; the Borgias are ready to move against their enemies; Catherina is determined to resist a siege; Cesare learns that Alfonso has become aggressive.