At the beginning of the story, Montresor is a bitter man who wants revenge against an associate of his named Fortunato.
Montresor and Fortunato meet each other at carnival & Fortunato is drunk and says how much he loves his wine so this is the perfect time for Montresor to set his trap
As Montresor is luring Fortunato into his trap, he realizes that Fortunato is not in very good health so he attempts to turn back from the journey but Fortunato refuses
After Fortunato insults Montresor for the last time by not calling him a Mason, Montresor chains Fortunato to a wall and begins to cover that wall with bricks
At this point, Montresor is continuing to seal up the wall and he realizes that he feels guilty for murder but he quickly snaps out of it and stabs Fortunato with a sword a couple times
In the end, Montresor places the last few bricks and throws a torch down to burn Fortunato alive. As Montresor calls his name, only the sound of his jester bells respond and Montresor had never revealed the truth about Fortunato until 50 years later. "In pace requiescat", he said which means- "May he rest in peace"