There are several ironic elements in the story, which include Fortunato's name, his outfit, and the lively setting. The story is set during the Italian carnival season, which is a festive time of year when citizens celebrate, drink alcohol, and party with their neighbors. The setting is similar to Mardi Gras, where people gather to enjoy themselves and let loose. It is in this pleasant, joyful setting when Montresor preys upon his victim and successfully lures Fortunato back to his home, where he fulfills his revenge plot.
The setting is ironic because Fortunato is in serious danger in such a delightful, friendly environment. While people laugh, joke, and enjoy themselves during the carnival, Fortunato lets his guard down at the most inopportune time. The carefree, safe environment is ironically dangerous and hostile, which is what makes Fortunato's situation more terrifying and Montresor's actions more disturbing. The "supreme madness" of the carnival season and Montresor's black outfit offer him protection. In the chaotic, hectic setting, Montresor is able to go unnoticed.
Nobody would remember Montresor being present during the carnival, and Fortunato's friends would think he simply disappeared. Fortunato is dressed in motley, believes that Montresor is harmless, and does not suspect a thing, which is why the audience pities him and sympathizes with his character. Fortunato is also visibly intoxicated, which makes him more susceptible to Montresor's plot. Tragically, Fortunato falls for Montresor's artifice and experiences a terrible death.