Figurative enclosure began with the reader, drawn by Montresor into his space, assuming collusion and sympathy: "You, who so well know the nature of my soul" (Poe, 1090), tells the reader "you are with me in this, you understand." Fortunato was trapped too, by his greed and vanity, and into placing himself in the trap.
Montresor was also enclosed in his world of paranoia and revenge, a loner who perceived himself superior, who had no rational cause to kill. The absence of real motive here showed a mind locked into a cold, psychotic personality. He did not explain, "The thousand injuries of Fortunato I had borne", but provided glimpses of a focused, calculated, mental derangement in "I must not only punish, but punish with impunity." (Poe, 1090). If Montresor was mad, then he was locked in that space, without human feelings, taking victim and reader with him, to the horrific reality of a living death, enclosed in the catacomb walls. These and the journey to them, represented a metaphor for the convoluted workings of a deranged mind, while focusing on themes, plot, action and resolution.
Literal, real enclosed spaces become smaller and more threatening, reaching the horrific climax.