This scene is taken from Canto XXX of the Inferno, in which Dante and Virgil reach the tenth bolgia of the eighth circle where they witness the punishment of those guilty of impersonating someone in order to deceive others.  The two damned fighting viciously in the foreground are Gianni Schicchi (with the red hair) and Capocchio. According to the poem, Gianni Schicchi is punished with an insatiable, furious craving that causes him to bite the neck of Capocchio, an alchemist and falsifier of metals.