Scobie heads toward the Nissen huts. He thinks this could be the day when he starts the process of recovering from his life of sin. He nearly passes Helen on the road, but then decides to stop for her. She looks somewhat haggard. They sit in the car and she tells him that she heard about Ali's death. Scobie sadly admits that he is responsible for the boy's untimely demise. Helen reveals that she is planning to go away. She knows she is making him miserable and the only solution is for her to leave the colony. It will be immensely difficult to separate, but at least he can be a Catholic again. When Helen tells Scobie that he will finally have peace, he wonders how she learned so much tenderness and maturity.
They kiss and Scobie's heart beats quickly. Helen instructs him to close his eyes so he will not see her leave. Despondent, he prays for death but it does not come. Scobie tells Helen not to leave town and promises her that he will think of something. Privately, he decides what he is going to do. Later, Scobie sits with Louise at home and thinks about Ali. Louise says that she is sorry about the boy, but Scobie knows that Ali's death has had little impact on her. Instead, Louise wants to talk about having a party for Christmas and Scobie replies that the holidays are still far off. He thinks that Louise seems smug and contented as she secures his further damnation. Scobie wishes he could still pity her and find her unattractive again but now there is a gap between them. His hatred for Louise dissipates momentarily with the realization that she will never be the wife of the Commissioner of Police.
Scobie thinks about how he never lied in his diary. He decides to start adding to the older entries, describing being sleepless and feeling pain. He does this for the coroners and insurance agents who will be reading it after his demise. Scobie meets with Dr. Travis and shares his fictional woes. He brings up his sleeplessness and pain and mentions the possibility of angina. Dr. Travis gives him a prescription for Evipan (a sleeping pill). After leaving the doctor's office, Scobie thinks about the right date for his death. He must be very careful to hide the fact that his death is a suicide. He decides to take a dose of Evipan each night and save a bit for the tenth night. His plan must be perfect because suicide is the worst crime a Catholic can ever commit. The finality of Scobie's decision gives him peace.
Scobie stops at the church and feels envious of people praying. He realizes he has chosen Helen and Louise's happiness over God's. It is harder to bear their suffering because they are tangible beings, unlike God. Scobie knows that he cannot keep going to Communion and Mass and pretend he is not a sinner. He tells himself that God will forget him once he is gone. In his internal monologue, Scobie addresses God, whom he believes will be "better off" after the loss of Scobie, "once and for all."
Another contradictory monologue impedes on Scobie's thoughts - as if God is responding to his statements. This second voice asks Scobie to trust Him and ask for repentance. He asks Scobie to stop lying to God and to himself. Scobie, however, cannot trust God. He holds God responsible for the "feeling of responsibility that [Scobie] has always carried about like a sack of bricks." He doesn't want anyone else to suffer in order for his own salvation. Scobie believes that he and God are at an impasse, and Scobie cannot keep insulting God at his own altar. He is firm in his decision.
The diary entries prove to be perfect. Scobie rejects the Commissioner position and tells Louise it is because of his pain and sleeplessness. He prepares for retirement. Scobie's brain feels clear after so long but there are still deceptions to put into play before his final moments. He does not want anyone to suspect his suicide at all. He goes to Helen's hut, but she is not there. He wishes he could leave a note for her, but that would destroy the farce he has so carefully constructed. Instead, he just writes "I love you" under a stamp in Helen's album.
That night, Scobie sits with Louise. He feels a strange sensation as he goes about certain regular routines for the last time. Louise talks about where they will live after Scobie's retirement. Finally he decides that he must do it, but he feels sick. Scobie wonders if he can really go through with the suicide. Louise asks how Scobie is doing, making him reflect on how her love is like a "death sentence" (263). He looks at Louise and sees her getting older and less beautiful but wonders if this is love because it is real and not fleeting. Scobie thinks that he is going to protect her by dying.
Louise goes upstairs. Careful to keep his tone light-hearted, Scobie tells Louise he loves her. He drinks some whiskey and tries to summon the courage to take the sleeping pills. One voice encourages him to throw them away, go to bed, and lead a normal life tomorrow. He rejects this voice and takes the pills. Then, Scobie waits for death, wondering what it will feel like. A cloud drifts into the room. He wonders what he has to feel sorry for. He tries to sit upright but wonders why he has to. He calls out for Ali, but it seems like someone is calling for him. He stands up. There is darkness and a storm inside of him; someone needs him. He says, "Dear God, I love..." (263). He does not feel it when he falls to the floor.
Louise and Wilson are talking. She says people have been very kind about Scobie’s death. She asks about Helen and Wilson says he has seen her with Bagster and she seemed a little drunk. Louise scoffs that Helen has no dignity. Wilson asks Louise if she knew about the affair and Louise admits that Mrs. Carter had written her a letter with the news, and that is why Louise came back from South Africa. It turns out that Scobie was not being as clever as he thought. Louise says that she can believe the rumors about Scobie and Yusuf now. She sighs and says that she did love Scobie.
Back at the house, Wilson asks Louise if he can see Scobie’s diary and Louise assents, saying that Scobie has no secrets left. Wilson notices that the descriptions of sleeplessness and pain are written later in a different color ink and points out the inconsistencies to Louise. She is horrified by the insinuation that Scobie committed suicide - because after all, he was a Catholic.
Meanwhile, Bagster and Louise return to her hut after frolicking on the beach. Bagster is sloppy and drunk but Helen tolerates him nonetheless. They have sex but she is not very excited by it, so Bagster gets mad wonders how Helen could love Scobie and not him? Eventually, Bagster's anger passes and he decides to leave Helen's hut. Helen asks Bagster if he is religious and he says he believes in God. Mournfully, Helen says she wishes she did believe. She tries to pray but trails off.
Louise speaks with Father Rank, who is a little perturbed at Wilson’s new observation about Scobie's diary entries. He consoles Louise with the fact that Wilson only knew Scobie’s sins, not his virtues, which is what is most important about a person. Louise thinks that Scobie must have known he was damning himself and Father Rank agrees. Louise feels like there is little hope in praying, and starts to mention the Church, but the priest interrupts her and says the Church does not know what goes on in a human heart. Father Rank muses that of all men, Scobie seemed to really love God, despite his sins. Louise agrees and says he loved no one else. Father Rank replies that she is probably right.
The final sections of the novel find Scobie embracing action instead of futility and choosing to commit suicide rather than to go on lying to God. The essential question at the end of the novel is whether or not Scobie was damned. Did Scobie eventually go to Hell for his sins, or, as Father Rank gently suggests, did God see into Scobie's heart and offer him salvation on account of his faith and love?
Father Rank's insinuation that God could pardon Scobie's suicide contradicts the teachings of the Catholic Church. Greene had a particularly liberal view of Catholicism, which led author Evelyn Waugh to deride The Heart of the Matter as "mad blasphemy." Wilhelm Hortmann discusses Greene's faith in his scholarly article, noting the author's "warmhearted defense of the despairing sinner, his scorn of pious bigots, and his claim that the Church may know all the rules, but 'it doesn't know what goes on in a single human heart'." Some devout Catholics might find these views to be dangerously close to heresy, Hortmann explains, as Catholicism does not allow for "borderline cases" of sin in which the doctrine of damnation does not apply.
Scobie certainly does not make the choice to take his own life lightly. While he decides to follow through only after his encounter with Helen on the road, the idea has clearly been germinating in his mind for a long time. In addition, Scobie's methodical planning and his careful endeavors to disguise the true cause of his death also denote his premeditation. Early on in the novel, Scobie claims that he could never commit suicide because it is a mortal sin, but he still feels tremendous sympathy for young Pemberton and muses that God would no doubt show Pemberton grace for his youth and naiveté. Hortmann writes, "Greene voices a humane sentiment but he is obviously at variance with the explicit teaching of the Church concerning suicide...the suggestion...is that the Church is limited in its understanding of and provision for human failure, that we cannot expect true justice from it and that an all-understanding and all-merciful God will decide differently." The idea that the individual is more powerful than the divine authority disconcerted many of Greene's Catholic readers and reviewers.
In Scobie's conversation with God before his suicide, he claims to still love God even though he no longer trusts Him. In this back-and-forth, Greene suggests that the Catholic God needs to have a deeper understanding of the human spirit and its failings. Greene uses Father Rank as his mouthpiece; when Louise asserts that Scobie damned himself, Father Rank tells her not to focus on what the Church says. He also says that Scobie "really loved God" (272). Rank's words appear to be problematic on the surface. How could Scobie have loved God if he violated His laws?
In fact, Scobie knew that he could not take back what he had done and could not fully repent, either. Because of this, he felt that he would be insulting God every time he approached the altar. He says to himself that God will be "at peace when I am out of [His] reach" (258). Elliot Malamet points out that Scobie's suicide comes from "the burning desire to be out of sight [which is] also clearly revealed in his words." However, Scobie's overwhelming sense of responsibility leads him to take action to protect those he loves (including God). He writes Helen a little note and, with his false diary entries, Scobie attempts to save Louise from the shame of having been married to a man who killed himself.