The mood of "The Cask of Amontillado" can be described as eerie, foreboding, suspenseful, and ominous. In order to create this unsettling atmosphere, Poe utilizes several literary techniques, which include setting, dramatic irony, foreshadowing, and imagery. At the beginning of the story, Poe introduces the reader to the vengeful narrator, Montresor, who elaborates on his desire to get revenge on Fortunato for causing him a "thousand injuries."

As Montresor's plot unfolds and he interacts with the unsuspecting Fortunato, dramatic irony creates an agitated, foreboding mood. The reader knows that Montresor is manipulating his enemy but is unsure how he plans on getting revenge. The more Fortunato trusts Montresor and follows his lead into the catacombs, the more anxiety and suspense the reader experiences. By purposefully leaving the details out of Montresor's revenge plot, Poe creates an uneasy, disturbing mood.

Poe also uses setting to create various moods. The carnival setting produces a hectic, chaotic atmosphere, which reflects Fortunato's intoxicated state. The irony of Fortunato's jester costume also contributes to the unsetting mood and foreshadows his demise. The reader is aware that Fortunato is literally playing the fool and will end up suffering in some terrible, unknown way.

Once the main characters enter Montresor's underground vaults, the dark crypt creates a threatening, terrifying mood. The visual imagery of decaying skeletons, scattered bones, hanging nitre, and broken bottles is unnerving and ominous. The damp, cold atmosphere inside the vaults also creates a chilling mood, and the desolate catacombs foreshadow Fortunato's ultimate fate. The reader recognizes that Fortunato will never return, and the horrific nature of his death is severely disturbing.

Poe uses foreshadowing, which is hinting at what is to come later in the story to create a mood of foreboding and unease in this tale. It opens with Montresor ruminating on the many injuries he has suffered at the hands of Fortunato. In this beginning, Montresor also outlines his theories about revenge. This, from the start, raises in the reader's mind the idea that something terrible will happen.

A chief way any writer creates mood is through imagery, description that uses the five senses of sight, sound, taste, touch, and smell. Poe was a master of using imagery--often quite imaginatively--to raise a sense of horror. In this story, he uses sight, sound, and touch to create an increasingly terrifying mood.

Memorable visual images include the dark catacombs lit only by the flame of Montresor's torch, the black silk mask Montresor covers his face with, and the piles of human bones the two men pass. Memorable sound images include the tinkle of Fortunato's jester cap bells as he is led unwittingly to his doom and the echo of Fortunato's and then Montresor's responding screams as Fortunato is being walled up:

I replied to the yells of him who clamored. I re-echoed—I aided—I surpassed them in volume and in strength. I did this, and the clamorer grew still.

Touch imagery includes the damp and cold feeling in the catacombs.

All of this builds a sense of growing horror and foreboding that culminates in the way Fortunato is murdered.

One of the primary ways in which Edgar Allen Poe creates a dark and foreboding mood in his story "The Cask of Amontillado" is through the use of setting. It is in the pitch of night that Montresor happens upon Fortunato and invites him back to his abandoned estate. From there Fortunato and Montresor wander deep into the estates' underground vaults filled with decaying bones, narrow passages, and dark damp air. This setting creates a strong sense of foreboding and foreshadows Fortunato's unfortunate end. From the darkness of night, Montresor and Fortunato descend into the deeper blackness of the vault surrounded by death and decay. Poe conjures an end to meet this ominous setting as Montresor chains Fortunato to a wall at the back of a cave and buries him alive. Ultimately, Fortunato is swallowed up by the darkness before he even dies as his voice trails off and he stops responding to Montresor leaving the reader to wonder if he has met a more sinister fate than even Montresor imagined.

The dark and terrifying mood of "The Cask of Amontillado" is created largely through imagery. Poe uses powerful descriptions to show the dark underground catacomb:

...a deep crypt, in which the foulness of the air caused our flambeaux (torch) rather to glow than flame.

At the most remote end of the crypt there appeared another less spacious. Its walls had been lined with human remains...
(Poe, "The Cask of Amontillado," eNotes eText)

This is no ordinary wine-cellar, but a crypt serving both functions. Instead of spacious rows of barrels and bottles, there are tight corridors and slimy walls, with musty air that threatens to extinguish the torch. Walking through the catacomb causes Fortunato to cough violently, and the space is so dark that even the torches themselves are insufficient to light the way. The environment couples with Montresor's constant litany of "revenge" to create a claustrophobic, sinister mood.