When he reaches the destination to get back at Fortunato with revenge. Montresor tricks Fortunato that the wine is in the dark room. Then right when Fortunato steps a foot in the dark room he begins chain him up and start blocking him in with bricks.
Fortunato begins to awake as Montresor is piling bricks.Fortunato thinks he is pulling a prank but he aint. then Fortunato realizes it real and beg him to let him go.
Montresor was laying the last few bricks as Fortunato was freaking out and begging him to let him out and as the is finally closed up Montresor throws the torch in there so he can have that last bit of light. As Montresor is about to leave the only thing he heard was the bells on Fortunato's hat.