The Pit and the Pendulum
He's an unnamed man who was accused of crime (which was never mentioned) and ended up locked in a dungeon. While stuck, he tries to figure the size of the room and to escape danger. As the story continues, he begins to go mad but in the end pulls himself together and escapes completely.
They're the torturers who closely watch the narrator's every move and give him different punishments.
He's the man who rescued the narrator.