The setting of the gloomy catacombs works effectively to create atmosphere in "The Cask of Amontillado," especially in contrast to the high spirits of carnival time. Poe develops tension in many ways as the narrator Montresor draws Fortunato closer and closer to his inevitable doom. We know that Montresor is up to no good--that he is avenging a wrongdoing by luring Fortunato down to the catacombs: "THE thousand injuries of Fortunato I had borne as I best could, but when he ventured upon insult I vowed revenge." Fortunato doesn't know he is walking into a trap. His arrogance makes him continue further on despite the warnings Montresor knowshe will ignore: warnings about the cold and damp. When Fortunato says that a cold won't kill him, we pick up the increasing tension and the double meaning (that is--a cold won't kill him but something else WILL) when Montresor says "True." The tension escalates as Montresor gets Fortunato drunk and begins walling him in. As the e-notes guide to "A Cask of Amontillado" states, Montresor’s calm voice in the face of his evil intention also contributes to the tension and horror: "Even at the most terrifying moment in the story, when Fortunato realizes that Montresor intends to seal him up behind a wall, the narrator is calm and detached." It is the abnormal psychology of the psychopathic, vengeful Montresor that grabs us in this masterful story.