In "The Cask of Amontillado," readers learn about the murder of Fortunato as it is recalled by his murderer, Montresor. In this, Poe makes very effective use of the narrative subjectivity inherent to first-person voice.

Montresor is an unreliable narrator, highly disturbed, motivated by a vendetta for a perceived slight which we, the readers, know nothing about. We do not even know whether Fortunato committed any wrongdoing against Montresor to begin with (note that this perceived slight could have emerged from a misunderstanding, or it could have been entirely an invention of Montresor's own mind). In this sense, there is actually a great deal of background information that is entirely withheld from the narrative, bringing an underlying sense of uncertainty and ambiguity that pervades Poe's story as a whole.

In addition, Poe's use of first-person voice, especially when depicting the interactions between Montresor and Fortunato, provides a dramatic irony that enhances the story's suspense. (To be clear, dramatic irony exists when readers are made aware of plot-relevant information that the characters within the story are ignorant of.) In this sense, from the story's first paragraph, readers know about Montresor's vendetta and desire for vengeance against his perceived enemy, while Fortunato is not even aware that Montresor wishes him harm to begin with.

While dramatic irony could have been created through third-person voice as well, having this story told from Montresor's own perspective only heightens that underlying sense of tension, as we essentially follow alongside the murderer himself, reading as he leads his unsuspecting victim toward his death. At the same time, however, Montresor continues to withhold the critical information as to how he intends to gain his vengeance until the story's ending (where readers essentially learn alongside Fortunato about his grisly fate), a choice on Poe's part that further heightens the tension and suspense. In all this, Poe showcases a skillful use of first-person point of view.