The story opens on a ship with Dr. Macphail smoking his pipe. He is annoyed by the music produced by the mechanic piano, but he manages to find some peace on the deck. Soon he notices his wife talking to Davidsons, the missionaries, and he strolls over to join the conversation. The two couples befriended each other on the cruise based on their shared disapproval for other passengers, who spent their days and nights playing hazardous games drinking.
The next morning Dr. Macphail finds himself on the deck talking to Mrs. Davidson. As the ship is approaching land, Mrs Davidson remarks that she is glad that she and her husband were not stationed in this area. She also elaborates on the natives in their district of North Samoa, and their ‘shocking' marriage customs, to which the Davidsons responded by forbidding the natives from dancing, as they though these dances to be immoral and leading to immorality.
As the ship approaches the harbour, the travelers are able to identify a schooner full of natives ready to barter. Dr. Macphail is amazed by their medical problems, such as elephantiasis, and Mrs. Davidson can’t refrain from pointing out the indecency of their lava-lava clothing. She also proudly adds that at their islands they managed to eradicate the native clothing almost completely.
Later, Mr. Davidson joins the party bearing bad news. Apparently and epidemic of measles has broken out between the natives, and one of the members of the crew of the schooner that was supposed to transport the travelers has fallen ill too. Consequently, the schooner was forbidden from entering the harbor until it was certain that no other passengers were ill. This is particularly unwelcome information for Dr. Macphail, who insists he is urgently needed in Apia. What is more, it’s raining and there is no hotel on the island, so the two couples have no other choice than to rent out very poorly furnished room in a private establishment.
The travelers are unable to leave the island, so they spend their time together. Meanwhile, Mr. Davidson talks about the hard work that has awaited him when he first came to the Pacific and about his greatest achievement consisting of installing the sense of sin in the natives.
One evening when the Davidson and the Macphails are having dinner, they hear a gramophone and the clinging off glasses from the room downstairs, where a fellow traveler Miss Thompson resides. After a while Mr. Davidson exclaims that she must be from Iwelei, the Red Light district of Honolulu, and she must be carrying on her trade here. Outraged, the missionary decides to take the matter into his own hands. He rushes downstairs and hurls the gramophone on the floor, but his intervention is of no use, as he is thrown out and the party continues.
The next day during dinner, Mr. Davidson asks a native girl to set up an appointment for him with Miss Thompson. He visits her after dinner and remains for an hour. He comes back unsuccessful, persuaded she is an evil woman, but wows to pursue her 'to the uttermost parts of the earth’. Later, Dr. Macphail finds out that the missionary has asked the trader, Mr Horn, to forbid Miss Thompson from having her customers in. During the night, the doctor and his wife hear Mr. Davidson pray aloud for Miss Thompson’s soul.
Couple of days later, when the two pairs are dining, the door flings open on the dining room and enraged Miss Thompson enters. She is insulting the missionary and inquires about what he has been saying to the governor about her, because apparently she was asked to leave on next boat. She was to sail in 5 days on a boat to San Francisco.
The next day Miss Thompson pretends to be ill and calls Dr. Macphail to her room. She wants him to ask the missionary if he would let her stay for a fortnight, so she can take a boat to Sydney and get a clean job there. Macphail assures her that Davidson will not allow that, but he promises to ask.
Macphail’s prediction turns out to be right, but he promises Miss Thompson to go and see the governor himself. The governor sees the doctor’s point but he refuses to take back an order that he had already given, especially since Davidson threatened to complain about him back in Washington.
In the evening after dinner, Miss Thomson asks to see Mr. Davidson. She begs the missionary not send her to San Francisco because she would have to go to prison for three years, but he is determined to make her go there and accept her punishment. Miss Thompson has a break down and the doctor takes he back to her room. When he returns, the missionary asks everyone to pray with him for the young woman’s soul.
During next couple of days, Miss Thomson turns into a wreck of a person. She is apathetic and spends her days reading the bible and praying with the missionary. The situation is so bad that she even starts to look forward to her punishment because it seems like an escape from the intolerable situation. Meanwhile, the weather is horrid, it will not stop raining. On Monday, Miss Thomson receives a call telling her to be ready the next day at 11.
In the middle of the night Macphail is woken up by Mr. Horn. The trader leads him to the shore where a group of native people are already waiting. When they open up, the doctor sees the dead body of the missionary Davidson, with his throat cut from ear to ear, the razor still stuck inside of the wound. They conclude it was a suicide.
Dr. Macphail asks his wife to break the news to Mrs. Davidson. The missionary’s wife wants to see her dead husband, so the Macphails accompany her to the mortuary. On their way back, they hear a gramophone playing loudly in the house. When they come in, they see Miss Thomson, a changed woman, ‘in all her finery’ chatting up a sailor. Upon the sight of Mrs. Davidson, Miss Thomson spits into her direction. The recent widow runs upstairs, while the doctor attempts to confront the prostitute. She asks him what the hell is he doing in her room. Dr. Macphail is confused. Miss Thomson exclaims that all the men are the same, they are all pigs, in response to which the doctor merely gasps because he understands.