The anonymous narrator (who delivers his story in first-person) is being held prisoner and tortured as part of the Spanish Inquisition in Toledo, Spain. Because of the various tortures (many unnamed), his descriptions of the events are clouded, though the narrator--who at times seems deranged--clearly tells his story. Although he sees the judges, he cannot hear them as he is sentenced. When he next awakens, he is in total darkness and is uncertain whether he is alive or dead. Finally recognizing that he is still alive, he opens his eyes, but he can see nothing because of the blackness that surrounds him. He remembers the trial now, and that he has been sentenced to death; when he finally summons the courage to stand, he tries to determine the size of the place of his imprisonment. It is damp and the floor is slippery. Exhausted, he falls asleep; but when he awakens, he finds that food and water have been provided for him. When he again tries to map out the course of his cell, he slips and falls, and he realizes that he is lying beside the edge of some pit. When he drops a stone into it, he recognizes that the pit is a deep one. Again he falls asleep, and again food and water await him. It is obvious that his tormentors plan to keep him alive for further torture. This time, he falls asleep because the food or water has been drugged; when he awakes, he is able to see his cell more clearly. It is smaller than he suspected, with horrible figures carved on the walls. He is bound to some form of rack; food is nearby, but he cannot reach it. Above him he sees a picture of Father Time, holding some sort of pendulum. As rats scurry around him, he sees that the pendulum is descending and swinging from side to side; it's edge is sharp. It is meant to eventually cut him in half.
As the pendulum is about to cut into his flesh, the prisoner concocts a plan: Reaching for the last remaining bit of meat, he rubs it upon the binding about his hand; the rats swarm, and they eat through the binding. He frees his hand, unties the straps, and avoids the blade that would have killed him just seconds later. Seemingly free, another horror soon becomes evident: The walls are slowly moving inward, toward the pit. Just as he is about to fall, he screams. Suddenly, a trumpet sounds, and a voice is heard. The walls move backward. An arm reaches out to save him. It is the arm belonging to General LaSalle: The French army has arrived to save him just in the nick of time.