Albert and Beauchamp rush to Monte Cristo’s house, but are told that he is not receiving any visitors. However, the servant at the door reveals that Monte Cristo will be attending the opera that evening. Albert sends word to Franz, Debray, and Maximilian to meet him at the opera. He then goes to see Mercédès and asks her whether she knows of any reason why Monte Cristo should consider Fernand his enemy. Mercédès tries to convince her son that Monte Cristo is not an enemy and begs him not to quarrel with a man he so recently considered his friend.

After Albert leaves Mercédès, she instructs a servant to follow him all night and report back to her about his activities. At the opera, Albert storms into Monte Cristo’s box, insults him, and challenges him to a duel. The duel is set for eight o’clock the following morning and is to be carried out with pistols. Monte Cristo asks Maximilian and his brother-in-law, Emmanuel, to act as seconds, or assistants, at the duel.

Mercédès pays a desperate visit to Monte Cristo. Monte Cristo explains to Mercédès why he hates Fernand, showing her the false accusation that Fernand personally mailed to the public prosecutor so many years before. Mercédès falls to her knees and begs his forgiveness, declaring her enduring love for Edmond Dantès. She pleads with Monte Cristo to save her son’s life, beseeching him to take vengeance only on those who are guilty. Monte Cristo’s vengeful will is broken, and he swears that Albert’s life will be saved. However, his dignity requires that he still fight the duel, which means that he himself must die the next day.

Monte Cristo confides to Maximilian and Emmanuel that he plans to let himself be killed. He then demonstrates his almost superhuman skill with the pistol so that there will be no doubt as to whether he lost the duel on purpose. Albert finally arrives at the site of the duel, but rather than pick up his pistol he apologizes to Monte Cristo, telling him that he was right to avenge Fernand for wronging him. Monte Cristo realizes that Mercédès has told her son the entire story.

Albert and Mercédès both plan to leave all their worldly possessions behind and create a new life away from the sins of Fernand. As they are about to depart their home forever, a letter from Monte Cristo arrives. Monte Cristo instructs Mercédès to travel to Marseilles, to the house in which Louis Dantès once lived. Buried under a tree in front of that house is the money that Dantès once planned to use to start a family with Mercédès. He writes that this money, though a pittance, is rightfully hers and should be enough to support her comfortably for the rest of her life. Mercédès accepts the gift and declares that she will use it as a dowry to gain entrance to a convent.

Monte Cristo comes home to Haydée, who has been eagerly awaiting him. He realizes that he might love Haydée as he once loved Mercédès. Just as they bask in each other’s company, Fernand bursts in, enraged that his son did not follow through on the duel. Fernand then challenges Monte Cristo to a duel himself. Before fighting, Fernand demands to know who Monte Cristo really is. Monte Cristo disappears momentarily and then returns in the clothes of a sailor. Recognizing him instantly as Edmond Dantès, Fernand is stricken with terror and flees the house. He returns home to find his wife and son departing forever. As they pull away from the house, Fernand shoots himself in the head.

In these chapters, Mercédès demonstrates that she remains unchanged from the young woman she was in Marseilles, proving to Monte Cristo that he has been misjudging her all along. When Mercédès initially approaches Monte Cristo to beg for her son’s life, she tries to win his sympathy by reminding him that she is still the same woman he once loved. With his response that “Mercédès is dead,” Monte Cristo means to suggest that the innocent and good woman whom he once loved does not exist now as the wife of Fernand Mondego and perhaps never existed. Yet Mercédès proves wrong Monte Cristo’s estimation of her, revealing her monumental strength of character when she tells Albert about his father’s sins against Dantès. Her act requires incredible strength and courage, as it ensures that any last vestige of respect and love Albert bears his father will be destroyed. It would be understandable for Mercédès to allow Monte Cristo to die rather than harm her son’s psyche any further, yet she unselfishly chooses to spare Monte Cristo’s life.

Mercédès is often portrayed as the most intelligent character in the novel. Dumas notes that she is renowned all over Paris for her intelligence, and she is the only character able to unravel the mystery of Monte Cristo’s identity immediately. When Mercédès saves Monte Cristo’s life, she also proves herself the most noble character, the only one capable of forgiving those who may have done her wrong. She evokes even more sympathy by abandoning her wealth and comfortable life, refusing to live off of a fortune tainted by evil deeds. Convinced of Mercédès’s enduring goodness and innocence, Monte Cristo forgives her completely and attempts to amend for the fact that he is effectively depriving her of her husband and her wealth. Monte Cristo is now fully convinced, just as we are, that Mercédès is as virtuous as ever.

The initial exchange between Monte Cristo and Mercédès highlights an important motif in the novel: the significance of names. Upon entering Monte Cristo’s room, Mercédès addresses him as “Edmond,” causing him to stumble in alarm. She then insists that he call her “Mercédès” and not “Madame de Morcerf,” boldly defying Monte Cristo’s assertion that Mercédès is dead. What they actually argue about here is whether or not they remain, on any level, the good and innocent people that they once were. In calling Monte Cristo “Edmond,” Mercédès is proclaiming her belief that the kind and decent sailor she once knew still exists somewhere within the vengeful and mysterious Monte Cristo. By insisting that “Mercédès” is still alive, she is also trying to persuade Dantès that she remains the good woman whom he once loved—that despite his opinion, she has not become a greedy, haughty, and disloyal aristocrat.

The argument between Mercédès and Monte Cristo takes on an added layer of meaning when we consider the fact that their old names are the names of commoners while their new names are aristocratic titles. This detail links goodness with poverty and humility, as Dumas highlights a contrast between sincere, good, common folk and aristocrats who have become corrupted by wealth and power. Ultimately, both prove their enduring goodness: Monte Cristo by offering to die for Albert’s sake, and Mercédès by saving Monte Cristo’s life. They are both worthy of the identities that their old names connote. At their next meeting, they address each other by these names, reinforcing their essential goodness.