During the carnival in italy Montresor runs into Fortunato and offers to share a nice bottle of wine. However this bottle is in his catacombs it is late and Fortunato seems ill.
Montresor the narrator believes that Fortunato has inflicted a thousand insults upon him. It is because of these insults which are not named in the story that Montresor begins to execute his plot for revenge.
Montresor brings fortunate to his catacombs to taste his Amontillado, an expensive type of wine.