Dante awakens to find himself in on the other side of the river Acheron, where Virgil leads him down into the first circle of Hell. Unlike when he first entered, Dante doesn’t hear screams of terror, instead he just hears sighs of sadness and hopelessness. This is Limbo, where the souls of the virtuous pagans reside. These include Homer, Socrates, Plato, and Dante’s guide Virgil. These souls had no knowledge of Christ (being born before Him), and so died unbaptized.
In Medieval theology, these souls, though good, could not go to heaven. There only “punishment” was to live in desire of seeing God without hope.
After this fairly pleasant experience, Virgil leads Dante down lower into Hell, where things quickly get much worse.