What happens in Canto XXII of Dante's Inferno?

Canto XXII
The demon Barbariccia had been selected by Malacoda (along with others of his kind) to accompany the poets to a functioning bridge. To herald their departure, Barbariccia made a sound like a trumpet from his buttocks. Dante thinks about all the strange and noisy processions he has witnessed and none come close to matching the march of the devils, not even the Aretines. The Aretines were dezines of Arrezo, in Tuscany, Italy. There was also a French poet named Pietro Aretino, whose patron was the French King, François I. Aretino wrote bawdy verses and lived a very morally loose life.

“Vaunt-couriers have I seen upon your land,
O Aretines, and foragers go forth,
Tournaments stricken, and the joustings run,
Sometimes with trumpets and sometimes with bells,
With kettle-drums, and signals of the castles,
And with our own, and with outlandish things,
But never yet with bagpipe so uncouth
Did I see horsemen move, nor infantry,
Nor ship by any sign of land or star.
We went upon our way with the ten demons;
Ah, savage company! but in the church
With saints, and in the tavern with the gluttons!”

Despite the noise of their guides and their fearful aspect, Virgil and Dante follow. Although the fifth pouch is nearly lightless, Dante nonetheless stares intently at the water. He occasionally catches glimpses of sinners' arms and legs jutting out of the boiling river. The sight reminds him of dolphins’ backs rising above the water and of frogs briefly coming up above the surface:

“Ever upon the pitch was my intent,
To see the whole condition of that Bolgia,
And of the people who therein were burned.
Even as the dolphins, when they make a sign
To mariners by arching of the back,
That they should counsel take to save their vessel,
Thus sometimes, to alleviate his pain,
One of the sinners would display his back,
And in less time conceal it than it lightens.
As on the brink of water in a ditch
The frogs stand only with their muzzles out,
So that they hide their feet and other bulk,
So upon every side the sinners stood;”

As promised, the demons do not harm Dante but they continue to torment any sinner they are able to catch in the water. One of them, a demon named Grafficane, hooks one of the unfortunate souls, a “frog” to slow to avoid capture, with his sharp talons. As the demon hoists the shade aloft, its elongated form then reminds Dante of an otter:

“And Graffiacan, who most confronted him,
Grappled him by his tresses smeared with pitch,
And drew him up, so that he seemed an otter.”

Dante has learned the names of all of his demon-guides. He listens as Grafficane orders Rubicante to tear the sinner apart. But Dante begs Virgil to stop them and inquire who the sinner had been in life. Virgil complies and fearlessly approaches the tormented shade and asks where he was born.
Perhaps to delay his torturers, the shade offers much information. He says that he was born in Navarre, Spain, and that growing his father was a “wastral” (a waste of a person). He became close to King Thibault, whom he considers his adopted father. His sin was embezzlement and shady dealings with money in general. What the sinner does not offer, however, is his name.

"I in the kingdom of Navarre was born;
My mother placed me servant to a lord,
For she had borne me to a ribald knave,
Destroyer of himself and of his things.
Then I domestic was of good King Thibault;
I set me there to practise barratry,
For which I pay the reckoning in this heat."

The demon named Ciriatto will be delayed from his grim task no longer; he gouges a hole in the sinner, tearing him open with one of his forked horns. Barbariccia, too, is ready to attack but refrains; instead, he asks Virgil to continue his interrogation of the sinner. The demon warns, however, that he cannot hold off the hoard much longer.
Virgil speaks to the sinner again, but instead of demanding the shade’s name, Virgil asks him whether there are any more “Latians” (that is, Italians) under the river. The man replies that indeed there are, and that one is submerged very near himself, adding that he wishes he too were underneath the boiling waters rather than being subjected to the flaying of the demons above:

“The Guide: "Now tell then of the other culprits;
Knowest thou any one who is a Latian,
Under the pitch?" And he: "I separated
Lately from one who was a neighbour to it;
Would that I still were covered up with him,
For I should fear not either claw nor hook!"

Libicocco, one of the devils, will be delayed no more. He ferociously attacks the sinner while his compatriot, Draghignazzo, awaits his turn. Both are temporarily stopped by Barbariccia, who still wants to know the identity of this particular sinner immersed in the Phlegethon; he asks Virgil to find out:

"And Libicocco: "We have borne too much;"
And with his grapnel seized him by the arm,
So that, by rending, he tore off a tendon.
Eke Draghignazzo wished to pounce upon him
Down at the legs; whence their Decurion
Turned round and round about with evil look.
When they again somewhat were pacified,
Of him, who still was looking at his wound,
Demanded my Conductor without stay:
"Who was that one, from whom a luckless parting
Thou sayest thou hast made, to come ashore?"

Any delay means a few more moments of staying his torture, so the sinner is happy to comply. He tells Virgil that the man next to him is Friar Gomita from Gallura. Gallura is one of four districts in Sardinia, all of which were then a part of Pisa, Italy. In life, Friar Gomita had been a chaplain to Nino Visconti, a “guidice” or judge, of Pisa. Friar Gomita took bribes from convicted persons and secured their release. When Visconti learned of his chaplain’s avarice, he had Friar Gomita hung.
The desperate sinner also names another of his friends in the mire, Don Michael Zanche of Logodoro. This man had been the son of Emperor Frederick II and the governor of Sardinia under King Enzo. His sin had been the defrauding of Enzo’s widow after the king’s death, ploying her with flattery and obtaining a choice position as “Lord of Logodoro.”

"It was the Friar Gomita,
He of Gallura, vessel of all fraud,
Who had the enemies of his Lord in hand,
And dealt so with them each exults thereat;
Money he took, and let them smoothly off,
As he says; and in other offices
A barrator was he, not mean but sovereign.
Foregathers with him one Don Michael Zanche
Of Logodoro; and of Sardinia
To gossip never do their tongues feel tired.”

As the nameless Navarrese speaks, he spies one of the demons, Farfarello, coming to renew his torturous task but Barbariccia staves him off. Terrified, the shade offers to call others of his friends to the surface if only the demons will not attack him personally further:

"Tuscans or Lombards, I will make them come.
But let the Malebranche cease a little,
So that these may not their revenges fear,
And I, down sitting in this very place,
For one that I am will make seven come,
When I shall whistle, as our custom is
To do whenever one of us comes out."

The demons appear to find his attempts at delay humorous. Cagnazzo says he is aware of the shade’s trickery. Alinchino warns that if the sinner tries to dive under the water, he will be attacked from above. While they are laughing and boasting, however, the sinner actually does escape:

“Cagnazzo at these words his muzzle lifted,
Shaking his head, and said: "Just hear the trick
Which he has thought of, down to throw himself!"
Whence he, who snares in great abundance had,
Responded: "I by far too cunning am,
When I procure for mine a greater sadness."
Alichin held not in, but running counter
Unto the rest, said to him: "If thou dive,
I will not follow thee upon the gallop,
But I will beat my wings above the pitch;
The height be left, and be the bank a shield
To see if thou alone dost countervail us."
O thou who readest, thou shalt hear new sport!
Each to the other side his eyes averted;
He first, who most reluctant was to do it.
The Navarrese selected well his time;
Planted his feet on land, and in a moment
Leaped, and released himself from their design.”

The captors are enraged. They howl and then turn on each other. They lose their balance and fall into the boiling river. Unable to extricate themselves, Barbariccia sends the remaining Malebranche to get them out. While all the demons are so engaged, Virgil and Dante quietly take their leave.