The conversation between the two men in the catacombs partly relies upon the conversation that got them there in first place. Montresor has convinced Fortunato that he has acquired a rare and valuable wine, but he is unsure if it is the real thing or not; he had planned to seek the expert advice of a friend. Fortunato, being something of a braggart, and drunk, thinks he is suitable for the task instead. Montresor insists that Fortunato should not come, because the catacombs where he stored the wine are damp, and this will aggravate Fortunato's cold. In fact, every element of this setup has been carefully constructed by Montresor to ensure that Fortunato follows him into the trap.
As they descend, Montresor makes note once more of the dampness, saying Fortunato should go back, though Montresor knows this will only stir Fortunato's jealousy and stubbornness, and encourage him to go on.
Montresor also attempts to get Fortunato even more drunk, and they have a brief exchange, laced with dark and ironic humor on Montresor's part, about drinking to Fortunato's "long life", and how the Montresors are represented by a coat of arms that promises vengeance for an insult.
Montresor again entreats Fortunato to go back, but is met with refusal, and they crack another bottle of wine. Fortunato asks if Montresor is a mason, and by this he refers to the Freemasons, a fraternal order and "secret society". Montresor replies that he is, but shows Fortunato a trowel, a mason's tool, another moment of ironic humor and foreshadowing.
Finally they arrive at the site where Montresor intends to bury Fortunato, and their "conversation" comes to an end when Montresor chains Fortunato to the wall.
The majority of the conversation is characterized by Fortunato drunkenly stumbling his way past numerous pithy and dangerous implications spoken by Montresor, perhaps indicating an ego that factored into Montresor's inspiration to kill him.