There is a carnival going on in Venice, Italy which also takes place during the Italian Renaissance. This scene is meant to show the townspeople mingling and interacting at the carnival, and is meant to establish to the viewer what is going on.
In this scene, Montresor is debating on whether he should follow through with his murder plan for Fortunato. Here he is second-guessing his decision and thinking about some of the conflicts he will face if he follows through with the murder.
DO I WANT TO RUIN HIS HAPPY LIFE??!
SHOULD I TALK TO HIM FIRST?
BUT HE WAS SO MEAN :(((
IMAGINE THE GUILT.... I WOULD HAVE SO MUCH!
I NEED TO GET REVENGE!!
In this scene Montresor has persuaded Fortunato to enter the catacombs with him. This scene shows Montresor's pride and is meant to make Fortunato look inferior.
In this scene, Montresor has gotten Fortunato drunk. This is marking the end of their journey down the catacombs and into where Fortunato is about to get chained to the wall.
In this scene Montresor is building a wall around Fortunato. Fortunato is slowly realizing that Montresor is not joking anymore, and is very scared because Montresor is serious about killing Fortunato.
This scene shows the aftermath of the murder. The scene shows Montresor's remorse for what he did, and is starting to feel even more guilty.