A signal fire on the tower ahead; an answering fire from across the Styx. Phlegyas the ferryman comes with a boat — rowing in fury, thinking he carries new sinners. He is corrected. They embark and cross the black marsh of the Styx, its surface seething with the naked souls of the wrathful, who tear and bite and strike each other, screaming. Beneath the surface, Virgil tells Dante, gurgle the sullen — those whose anger turned inward, who poisoned their own lives with a resentful gloom. They are chanting through their muddy throats: we were sullen in the sweet air lit by the sun; now we are sullen in this black mud. It is the exact shape of their sin, made eternal.
A soul grabs the side of the boat — Filippo Argenti, a Black Guelf Florentine nobleman whom Dante despised. He demands to know who Dante is. Dante refuses to identify himself: go away with the other dogs. Argenti tries to climb aboard; Dante pushes him away. Then — in one of the poem's most charged moments — Dante says he wishes he could see Argenti plunged into the slime while still alive. Virgil embraces him and praises him for this. The wish is granted: the other souls tear Argenti apart. The satisfaction Dante takes in this is troubling and deliberate — the poem does not sanitize the human experience of righteous anger, which is also always tangled with something less righteous.
They reach the base of the City of Dis — the walled city within Hell that begins the lower region. Towers, minarets, the color of blood-iron, glowing red. At the gates stand more than a thousand Fallen Angels who refuse them entry. The gates slam shut. Virgil is rebuffed. He returns to Dante with a pale face, concealing his uncertainty behind false confidence. They wait.