The fifth trench is filled with boiling pitch and Dante cannot see anything in the pitch, which is continually bubbling. Suddenly, Virgil tells him to look out and pulls him to his side. Dante turns to see a devil running along, carrying a sinner on his shoulders. The devil tosses the sinner into the pitch, saying that the sinner will join other barrators there. (Barrators are those who exchange public office for money.) Other demons prod the sinner down under the pitch with their hooks and prongs, like cooks prodding meat into a stew.
The demons are terrifying creatures who seem to take delight in causing sinners pain. However, as understood within Dante's framework of divine justice, even these evil demons are paradoxically made to carry out the will of God, enforcing his divine justice through punishment.
Virgil tells Dante to hide behind a rock while he talks with these devils. When the devils see Virgil approach, they rush at him with their weapons, but Virgil tells them to halt. The leader of these demons, Malacoda comes to speak with Virgil. Virgil tells him that he is on a journey ordained by God's will. Frustrated, Malacoda relents and tells his fellow demons not to harm Virgil, who then calls for Dante to come out of hiding.
Virgil uses his powerful speech to deal with the hostile demons. In contrast to the evil creatures of hell who threaten and use physical violence, Virgil and other agents of God rely only on the power of words.
Dante hurries to Virgil's side. A few of the devils debate poking and stabbing at Dante for fun, anyways, but Malacoda reprimands them. He explains to Virgil and Dante that the bridge over the inner trenches was destroyed back when Jesus entered hell and so they will have to walk around to another place where they can proceed further toward the center of the eighth circle. He sends a group of demons to guide them.
While the devils are still mischievous and malevolent, Virgil's words have brought them sufficiently under control so that they will help Dante and Virgil. (However, Malacoda is not being entirely forthright and helpful here; at the end of canto 23, Virgil realizes that the devils were not telling the truth about the bridge being impassible.)
Dante is terrified and begs for Virgil to guide him alone, without the dubious company of demons. Virgil, though, reassures Dante that they will be fine, and the two poets take off with the group of demons.
Still susceptible to fear, Dante does not yet have complete confidence in his divinely appointed guide. Virgil's words again have a reassuring effect on Dante.