After Montressor decides how he is going to kill Fortunato he finds him at the carnival and mentions the Amontillado that he wants Fortunato to take a look at.
When Fortunato agrees to go with Montressor they have to make their way down to the catacombs where Montressor has the wine. However, Fortunato has a bad cough and MOntressor says they should go back but Fortunato refuses. Montressor then gives him some wine to "help" with Fortunato's cough.
Montressor then leads Fortunato further down to the catacombs until they reach the end of the catacombs.
When they reach the end of the catacombs Montressor makes sure to get Fortunato into the small room where he chains him up and being to mock him.
Fortunato tries to make Montressor turn what he is doing into a joke so that they can go back to the carnival.
Montressor finishes building the wall and throws a torch in along with Fortunato and then walks off felling good about what he did.