Fortunato does not suspect Montresor's plan. In fact, when they meet in the street during carnival, Fortunato is very glad to see him. Fortunato is dressed like a jester, and has been drinking. Throughout the story, Montresor exploits Fortunato's interest in wine. First, he tempts Fortunato by claiming he has purchased a cask of Amontillado, which is a dry sherry, but he is unsure if its authentic. Instead of asking Fortunato directly to examine the Amontillado, Montresor says he will ask another because Fortunato is busy, thereby playing upon both Fortunato's pride and greed.
Fortunato agrees to accompany Montresor home, where the servants have all gone to enjoy the festivities. Montresor grabs two torches and leads the way into the family catacombs, which are lined with nitre and cause Fortunato to cough. Montresor says they will go back, but Fortunato wants to see the Amontillado, claiming, "I shall not die of a cough," to which Montresor replies, "True—true."
While they walk deeper into the catacombs, Montresor describes his family's coat of arms and motto, which is "Nemo me impune lacessit," or "No one insults me with impunity." They also consume more wine. When Fortunato makes a secret sign of the masons, Montresor does not understand. Fortunato asks him for a sign he is of the masons, and Montresor produces a trowel from his cloak. Although Fortunato seems to be confused, he still wants to see the Amontillado, and they continue deeper into the tombs.
At the end of the crypt, there is a room lined with bones, with a pile of bones on one side. Fortunato, looking for the cask, steps into a small interior recess, and Montresor quickly chains him to the wall, taunting him with all the opportunities he had allowed for Fortunato to back out. Fortunato, in shock, can't comprehend what is happening as Montresor uses the trowel and stone and mortar buried under the pile of bones to wall up the crypt.
Fortunato comes to his senses and begins to moan and test the chains. Montresor waits until Fortunato stops shaking the chains, then continues boarding up the crypt. He raises the torch to look inside, and Fortunato begins screaming. Montresor is shocked, and unsheathes his sword, afraid Fortunato's screams will be heard. But reassuring himself of the solid walls of the catacombs, he also begins to yell, louder than Fortunato. After this, "the clamourer grew still."
Nearing midnight, Montresor is nearly finished the wall. When there is only one more stone to be added, Fortunato begins to laugh, and says in a sad voice that he has enjoyed...