Section III opens with the Harlequin urging Marlow to take Kurtz away from the station. The Harlequin recounts how he traveled deep into the wilderness and eventually encountered Kurtz. He again speaks of how Kurtz has opened his mind and made him "see things." Marlow envies the Harlequin's strength to push so deeply into the wilderness, but he doesn't envy his blind devotion to Kurtz. The Harlequin mentions that he nursed Kurtz through two illnesses. He also tells how Kurtz would often disappear into the jungle for days and that he often returned with ivory. When Marlow inquires how this was possible, since Kurtz had nothing to trade with, the Harlequin informs him that Kurtz took the ivory forcibly. Kurtz enlisted the aide of a local tribe, a group that he lived with and which actually worshiped him. The Harlequin mentions that once Kurtz wanted to kill him for a small stock of ivory he had acquired, noting that Kurtz could do such things this far from civilization. The Harlequin mentions how Kurtz hated living in the wilderness, but somehow he couldn't pull himself away from it. Kurtz would often go off to live in the jungle for weeks or months. When Marlow declares that Kurtz must be mad, the Harlequin protests, suggesting that Marlow's opinion would be different if he actually heard Kurtz speak. While the pair talk, Marlow scans the horizon with his binoculars. As he focuses on the main house, he notices that the poles he had originally thought were fence posts topped with wooden ornaments are actually poles topped with human heads.
At this point Marlow pauses his story to tell the men aboard the Nellie that the company claimed that Kurtz's methods had ruined the collection of ivory in the region. He also suggests that the heads were evidence that the wilderness had somehow changed Kurtz, that it had uncovered certain hidden aspects of his character.
The Harlequin mentions that he didn't dare take the heads down; they were the heads of "rebels," in essence those opposed to Kurtz. He also tells how the natives would crawl before Kurtz. The Harlequin breaks down as he tells Marlow how he has done his best to keep Kurtz alive, and how he believes Kurtz has been abandoned by the company.
As evening approaches, a throng of natives and the other members of the company suddenly emerge from the forest with Kurtz carried in on a makeshift stretcher. The Harlequin comments that Kurtz has only to say the word and they will all be killed. Marlow cannot hear Kurtz speak, but he notes Kurtz's ghost-like, wasted appearance: thin arms, exposed ribs, and gaunt face. Kurtz yells something, and the natives retreat into the forest.
Kurtz is taken to a small cabin aboard the steamer. Marlow senses that Kurtz recognizes him, believing someone from the company must have been writing about him to Kurtz. Marlow steps out of the cabin while the Manager has a private conversation with Kurtz, and in the distance, along the river bank, he sees several native warriors and a native woman.
Marlow describes the woman as very ornately dressed. She looks fierce and wild, though almost regal. She approaches the steamer, and when she reaches the boat, she faces them, throws her arms skyward, and then retreats into the jungle. The Harlequin fears the woman and suggests that he would have shot her if she had tried to board the boat; he also notes that he has spent the past few days trying to keep her away from the station house.
In the cabin, Marlow hears Kurtz lashing out at the Manager, proclaiming that he isn't as sick as the Manager might suppose. Kurtz asserts that he doesn't need to be saved, that it is he who has saved them. He exclaims that the Manager doesn't really care about his wellbeing, that he's only interested in the ivory. Kurtz then stresses that he hasn't finished his work in the region yet, accuses the manager of interfering with his plans, and vows to return to his Inner Station. When the manager exits the cabin, he pulls Marlow aside and tells him that Kurtz has harmed the company's efforts in the region, claiming that Kurtz's methods are "unsound." Marlow replies that he doesn't see any method at all, and the Manager agrees. When Marlow notes that he still respects Kurtz, he feels that he is no longer in good graces with the Manager. At this moment, Marlow senses a mental shift within himself; he feels himself repelled from the Manager and all that he represents and pulled toward the wilderness.
The Harlequin returns to converse with Marlow, telling Marlow that he believes the men from the company are out to get him. Marlow confirms his fears, informing the Harlequin that he heard the Manager and his uncle discuss hanging him. This sufficiently disturbs the Harlequin, who decides that since he can do no more for Kurtz that he should leave the camp. Before the Harlequin departs, he tells Marlow that Kurtz ordered the attack on the steamboat, believing that the men from the company would think he was dead and would abandon their mission. Kurtz, the Harlequin comments, fears that they will remove him from the station. The Harlequin laments the fact that he will never again hear Kurtz speak, once more noting how Kurtz had enlarged his mind.
Marlow awakens around midnight, remembers the Harlequin's warning, and decides to have a look around. A fire burning near the station house illuminates one of the company agents and several native workers standing guard over the ivory. Not too far into the forest he glimpses another fire, evidently the fire of Kurtz's followers. From the jungle Marlow can hear chanting and the beating of drums. He dozes but is awakened by frenzied yells from the forest. He looks in on Kurtz and discovers that Kurtz is no longer in the cabin. Marlow is shocked by Kurtz's disappearance, but he refuses to "betray" him by sounding an alarm. Instead, he leaves the boat in search of Kurtz.
Marlow locates Kurtz, who is crawling along a path, and Kurtz tells him to hide himself. Marlow asks Kurtz if he knows what he is doing, and Kurtz replies that he is sure of himself. Marlow sees that that they are very near the camp of Kurtz's disciples, and he fears that if Kurtz shouts it will mean death for him. Marlow tells Kurtz that if he doesn't return to civilization he will be utterly "lost" in the wilderness; Kurtz ignores the comment. Marlow then threatens to harm Kurtz if he raises an alarm, but all Kurtz can do is repeat is that he had great plans for the region. Alone in the darkness, Kurtz and Marlow converse, and Marlow sees that somehow Kurtz's isolation in the wilderness awakened a very primitive and brutal nature within him. He sees Kurtz as a man whose mind is sane but whose soul is mad, a man who has been profoundly changed by his deep introspection. As if shouldering a heavy burden, Marlow carries Kurtz back to the boat.
The next morning Marlow, Kurtz, and the rest of the company men depart the Inner Station aboard the steamer. Kurtz has been placed in the pilot house. A massive assembly of Kurtz's followers files out of the forest and lines the riverbank, loudly protesting as the boar pulls away. The woman Marlow saw the previous night comes to the front of the crowd and approaches the water's edge. She raises her arms and shouts something unintelligible; the entire thong of natives repeats her words. Marlow asks Kurtz if he understands the chant, and Kurtz, with a distant, longing smile, replies that he does. Marlow notices that the company men on deck have readied their arms, so he effectively disperses the crowd of natives by repeatedly sounding the boat's whistle. Only the woman remains standing at the water's edge, her arms outstretched toward the boat. As the boat pulls away, the company men begin firing on the natives.
Marlow notes how the return trip was much more rapid than the journey up river. Though he believes that Kurtz's life is slipping away, he comments that the Manager seems satisfied by the events. Marlow feels that with Kurtz's death, he too will be ostracized. During the trip, Kurtz speaks to Marlow about his doings and accomplishments in the wilderness; Marlow struggles to make sense of his talk. In Marlow's mind, Kurtz's body may be ravaged, but his spirit remains strong. The boat breaks down, and Marlow is forced to stop for repairs. He notes that the delay somehow destroys Kurtz's confidence. One morning Kurtz gives Marlow a bundle of papers and a photograph, telling him to keep them from the Manager's prying eyes. Marlow seems to be getting run down physically.
For a time, Marlow is kept busy attending to the ship's repair, and when he next encounters Kurtz, one evening in the small cabin, Kurtz tells him that he is awaiting death. Marlow brushes off Kurtz's comment, but then watches as his life ebbs. Kurtz's final words are "'The horror! The horror!'" Marlow extinguishes the candle, exits the cabin, and joins the other men for dinner. A short time later the Manager's personal attendant enters and announces that Kurtz is dead. While the others rush to Kurtz's cabin, Marlow remains seated and finishes his dinner in the dim lamplight. The next day Kurtz is buried "in a muddy hole."
Apparently Marlow falls ill, as he suggests that the company men nearly buried him too. Marlow notes how he too had come to the brink of death, but unlike Kurtz he had nothing significant to say regarding the experience. Marlow suggests that perhaps it was because Kurtz stepped over the line into death that he had something to say about it.
When Marlow comes to his senses, he is back in civilization, but he laments the fact. He looks upon the people of the city with contempt, believing them incapable of comprehending the things he learned in the wilderness. His aunt attempts to nurse him back to health, but he notes that his body wasn't the trouble; it was his mind. Marlow retained the papers Kurtz gave him, refusing to give them to the Manager on the boat and again refusing to give them to a man who comes looking for them after his return. The man argues that the documents are the rightful property of the company and must contain important knowledge about the region Kurtz was occupying. Marlow replies that the documents don't concern commerce at all and offers the man Kurtz's report to the Society for the Suppression of Savage Customs instead. The man refuses to take the report. Two days later another man, claiming to be Kurtz's cousin, appears; Marlow gives this man a few unimportant letters. Later a reporter visits Marlow, seeking information about Kurtz, and Marlow gives this man the report for publication.
Marlow remarks that all he retains of Kurtz's possessions are a few letters and a portrait of Kurtz's fianc�e. He decides to seek out the woman so that he may completely divest himself of Kurtz. On his way to her house, he is haunted by his memories of Kurtz in the jungle.
When Marlow is received at the home of Kurtz's fianc�e, it is getting dark. He notes that the woman is dressed in black. Though it is a year after Kurtz's death, she is still in mourning. She is not young, but seems dedicated to Kurtz's memory. They sit together, and seeing the packets of letters she asks if Marlow knew him well. Marlow replies that people get to know each other in a very short time in the wilderness. He reveals that he respected Kurtz, and she tells him that she needs to know Kurtz's last words. She speaks of Kurtz's greatness and the great loss the world faced with his death. She notes that for all of his greatness, nothing remains but the memories she and Marlow possess. She again implores Marlow to repeat Kurtz's last words. To himself, Marlow asks, "'Don't you hear them?'", implying that Kurtz's words are echoing all around them. In the end, however, Marlow lies and tells her that the last word Kurtz spoke was her name. This seems to soothe her.
Marlow concludes his tale by telling the men of the Nellie that he understands his betrayal of Kurtz's memory, but offering the truth would have been "too dark-too dark altogether." In the last lines of the story, the narrator comments how the tide had changed; it was now flowing back into the ocean, to all corners of the earth, "into the heart of an immense darkness."
Marlow's conversation with the Harlequin illustrates just how far Kurtz has departed from his initial plans. Kurtz is performing some very brutal actions to acquire his ivory and to, perhaps, satisfy his personal needs. Though it is never directly stated, enough evidence is offered to conclude that the natives are actually worshiping Kurtz. Whereas in Europe Kurtz had been simply one man among many, deep in the interior he is a god, to be worshiped and feared. Kurtz's wasted body is symbolic of his degraded morality. As Marlow notes, his mind is clear, but his soul is corrupt.
The native woman is one of the more interesting characters in the tale. Like the European women, she too has benefited from the quest for ivory, for she is ornamented in it. But she is the dark counterpart to Kurtz's fianc�e back in Europe, his "intended." Whereas his fianc�e sits at home patiently awaiting her suitor's return, the native woman actively pursues Kurtz, refusing to fear the company men, even when they are firing upon the natives.
When the Manager claims that Kurtz's methods are "unsound," he is applying a European definition. On the surface, the company operates under traditional business principles; there is a clear hierarchy or chain of command, as well as a perceived right and wrong way to act, and the company men are expected to respect this approach. However, the Manager's use of the term "unsound" calls into question the soundness of his own principles. It can be argued that the European method is just as unsound as Kurtz's method, since it so negatively impacts the native population. Kurtz, of course, adopts his own methods. He works alone and wants no interference from the company. Marlow's remark that he sees no method in Kurtz's actions is not an affirmation of Kurtz's insanity but rather an indication that Kurtz has divested himself of all traditional, European methods. Kurtz is no longer playing by "civilized" society's rules. It is, of course, interesting to note that Kurtz is the most successful agent.
Kurtz's revelation to Marlow, his recognition of "the horror" that lies at the heart of human nature, can interpreted in many ways. Regardless of how the phrase is interpreted, it must be recognized that it represents a significant transformation of Kurtz's philosophy. His experiences in the inner Congo have induced a very deep soul searching; he is a markedly different man when he dies-so too is Charlie Marlow.