Montresor has finally led Fortunato into the place where he shall be buried. He's chained him up and he has almost finished building the wall. He begins talking to him, making sure his plan has worked and that Fortunato has realized his fate.
Now, Montresor has one brick left to complete the burial. He calls for Fortunato once more, with no answer for he has realized his fate. Montresor throws in a torch and finishes the wall, feeling accomplished. He then stacks the remains of the other people in the catacombs in front of Fortunato's burial.
As Montresor is leaving, his heart grows sick, but not for Fortunato. He feels sick that the catacombs are so damp for the other passed souls in them. No one will touch the tomb for the next 50 years.