The sinner just addressed by Dante stops eating the head for a moment (wiping his mouth grotesquely on the other spirit's hair) to talk to him. The spirit recognizes that Dante is from Florence and agrees to tell his story. He is Count Ugolino from Pisa and he is eating the head of Archbishop Ruggieri, who imprisoned him along with his sons in a tower, where they starved.
For starving Ugolino, Ruggieri is now forever the victim of Ugolino's appetite.
Ugolino tells Dante that he is cruel if he does not weep at his story. One morning in the tower where he was starved to death, Ugolino began gnawing at his own hands and his sons told him to eat them instead, willingly sacrificing their own bodies. Ugolino stopped biting his hands, seeing how it troubled his sons. Over time, his sons died one by one and then Ugolino says ambiguously that "famine did what sorrow could not do," (33.75). After telling his story, Ugolino sinks his teeth into the Archbishop's head again.
Ugolinio implores Dante to pity him, and perhaps he would have at the beginning of his journey. But by now he has learned to moderate his response to the suffering souls of sinners. Ugolino's final line is ambiguous: did famine kill him, which his painful sorrow could not do? Or did famine compel him to eat his own children?
Dante cries out against Pisa. Although Ugolino betrayed Pisa in its disputes with other Italian cities, his children did not deserve to be punished along with him. Dante and Virgil leave Ugolino behind and Dante sees some tortured souls lying on their backs in the ice, unable to weep because their tears freeze over their faces.
Dante again uses an individual sinner's story as an opportunity to criticize an Italian town. He has come a long way from the man who fainted from pity at Francesca da Rimini's story, as he coolly moves on from Ugolino.
Dante feels a wind and asks Virgil what is causing it. Virgil tells him that he will see for himself soon enough. One suffering soul begs Dante to pull the layer of frozen tears from his face, so that he can cry once more (even though these tears will again freeze over his face). Dante agrees to on the condition that the spirit tells him his name.
This soul begs for some form of pity from Dante and Dante seems willing to grant it (but see below). Having recognized his power as a poet to grant fame, Dante uses it to bargain with this sinner.
The spirit identifies himself as Friar Alberigo, who killed his own brother after inviting him to a dinner. Dante asks if Alberigo is already dead and Alberigo says he isn't, but that this region of hell called Ptolomaea (reserved for those who betray guests) can hold souls even before they have died. The bodies of these people, bereft of their souls, are then possessed by demons on earth. He points out another suffering soul to Dante: Branca d'Oria, who Dante knows to be alive.
Alberigo and Branca are chilling examples of the connectedness of earth and hell. Their bodies walk on earth, controlled by hellish demons, while their souls dwell in hell. They also offer Dante an opportunity to slander a contemporary, by writing that Branca's soul is actually already in hell.
Branca had invited his father-in-law to a banquet and killed him there. Dante is incredulous that Branca's soul could come here even before he dies. Alberigo answers that Branca's soul came here as soon as he committed the murder, arriving even before the murdered father-in-law found his own place in hell. Alberigo asks Dante to release the ice from his eyes now, but Dante refuses. Dante laments Genoa, where Branca was from, as a horrible place where one of its citizens walks around with his soul already in hell.
Dante's behavior toward Branca may seem cruel, as he denies him the help he promised, but from Dante's perspective it is justified behavior toward a sinner against God. As with earlier sinners, Branca offers Dante a chance to criticize another local Italian city.