One drop of rain falls to the ground, then more drops and finally the rain becomes heavy, filling the rain barrel. The rain falls on palm leaves and other tropical plants.We are in Pago Pago, a village in an American Samoa isle, where Marines are stationed.For residents of the village, life is simple, involving fishing.A steamer en route to another port, is temporarily quarantined there when one sailor appears to have contracted cholera. Because of the heavy rains, the ship must stay longer than anticipated.Five passengers on the boat must come ashore. They are Alfred Davidson (Walter Huston), a missionary, his wife Martha (Beulah Bondi), Dr. McPhail and his wife (Matt Moore and Kendall Lee), and Sadie Thompson (Joan Crawford), a prostitute.The only accommodations are at a general store that doubles as a hotel, run by Joe Horn (Guy Kibbee) and his native wife (Mary Shaw). Mr. Horn is a genial and usually drunk innkeeper, who fusses, chortles, philosophizes, and who readily admits that he is escaping from America during the Prohibition years.On the boat prior to disembarking, the quartermaster receives some buddies from the Marine base, and he introduces them to Sadie, whom he had met in a Honolulu establishment of ill repute. They treat her like a friend, a comrade, not a lowly piece of scum or sexual object. Her interest is piqued by the shyest in the group, whom she names Handsome, although he is known as Sergeant Tim OHara (William Gargan). She smokes, jokes, and drinks with the guys, and asks them to take her belongings to the hotel.At the hotel, Sadie sets up her Victrola to play music and dances with Tim and others. Mrs. Davidson is annoyed at the antics of the wanton woman, and complains to Mr. Horn, but he says she is just a friendly person having fun. Mrs. Davidson then confronts the group telling them they should be ashamed to be partying up on the Sabbath. Sadie tells her to mind her own business, yet, in a spirit of compromise, moves the Victrola, music, and party into her own room.Mrs. Davidson persists in complaining about the intolerable noise to her husband. He goes to see the island governor, but is told there isn't any reason to evict the young woman, and anyway it will all stop in a few days.Dr. McPhail, who has a philosophical bent, and the innkeeper Mr. Horn have no objection to Sadie, and make mild comments in defense of her rights, but Mrs. Davidson hardens and insists that her husband put a stop to the activities in Sadie's room immediately.The Reverend knocks at Sadie's door and enters, shouting ensues, and the Reverend is forcibly ejected by the guys in Sadie's room. She comes out and in no uncertain terms tells him to knock and wait to be invited in before he barges into a lady's private room, or else put up with what he got.Sadie Thompson, fights back like lightning whenever something or someone, like Davidson, objects to her lifestyle.The rain does not stop, the hotel guests must stay in close proximity to each other, and from time to time Sadie and the Reverend meet. When only the two of them are present, he talks calmly to her at first, almost sympathetically, because his pastoral duty is to convert sinners, not hate them. Again, at first, she responds well, saying she is sorry to make trouble, and wants to be a good person. But in repeated opportunities their initially respectful conversation turns ugly as he makes demands for an instant, complete turnaround in her behavior. Davidson finds is that his religious persistence annoys her and that Sadie can be as demanding and powerful as he in her responses.The Reverends frustration, amplified by his wife's entreaties, convince him to go back to the governor and threaten him with consequences if he doesn't get rid of Sadie, as the missionary claims to have powerful connections back in Washington.The governor, a weak man, as the Reverend describes him, acquiesces and orders Sadie deported back to San Francisco on the next available ship.Meantime, Tim has fallen in love with Sadie and talks to her about having a future together in Sydney, despite his knowledge of her past. He describes to her how one of his best buddies has married and has a family with a girl who used to work at the same establishment as Sadie, back in Honolulu. As that couple initially met "illegally", seeing each other at their worst, they can now appreciate seeing each other at their best.As Sadie has continued to meet with Tim and some of his buddies, and not given up music or dancing or drinking and smoking, the Reverend makes a formal complaint to the military authorities about Tim having attacked him, and Tim is sent to the brig.Sadie is fearful of being sent back to San Francisco, and is without support from Tim, so she weakens and returns to talk to the Reverend, pleading with him to let her wait for another ship a few days more and go to Sydney instead.The Reverend keeps asking her questions, and changes his emphasis somewhat, talking to her about God's infinite love and forgiveness and the need for repentance about the past, rather than her current behavior, and he begins to have an influence on her. She eventually admits to him that she is wanted in San Francisco for crimes that she did not commit, but was framed for. But the Reverend keeps talking to her about how one must accept suffering, even if unjust, even if she is innocent, because of past sins unrelated to her conviction.She begs Davidson to allow her to remain on the island a few more days; her plan is to flee to Sydney instead.Sadie convinces Dr. MacPhail to try to intercede in her behalf, first with Davidson, then with the governor, but both intercessions are in vain.She confronts Davidson again, not listening to his sermonizing, and yells back at him with such vehemence that he begins to pray out loud instead of listening to her or answering her. As he gets louder and repeats the Lord's prayer as a hypnotic incantation, she begins to repeat some of the words, starting with forgive us our trespasses. With each new repetition she learns and repeats more words of the prayer, until she is saying the whole prayer along with him.Soon, Sadie has become another woman through the influence of Davidson and the effect of his prayers. She repents of her old life and is disposed to travel to San Francisco and accept the punishment of the law in expiation for her sins. Davidson feels he has succeeded in saving Sadie's immortal soul by cleansing her from her sins.Eventually Sgt. O'Hara gets out of the brig and comes looking for Sadie. The soldier cannot believe the transformation in Sadie.The "reformed" Sadie is much more beautiful with less makeup and a classical dress than the lurid Sadie, yet Tim believes her spirit is broken, that she is a mere shell of her former self. He tries to persuade her to go away with him, rather than return to the U.S. to "pay for her sins" as the missionary has convinced her she must, but she is fully under Davidson's spell and refuses.Finally the Golden Gate steamer to San Francisco arrives, and Sadie's last evening in the island is in course.The natives are dancing their Polynesian music and their drums emphasize the sensual nature of life in the tropics.Lolling indolently, Joe Horn reads out loud to Dr. McPhail from a small book something that sounds like Ecclesiastes-- for a moment, we nearly believe that Davidson has converted him, too. Then, finishing the passage, he intones, "Thus spoke Zarathustra.... Good old Nietzsche!"Meantime, Davidson feels strong emotions at the prospect of being separated from Sadie, and finds himself being led into unfamiliar temptations. He seeks her out and, without using his preaching oratorical style, tells her she need not go to San Francisco after all, and for the first time he is seen holding her by her upper arms. He is telling her in a hypnotic voice, over the native drums in the background, that she is now "radiant, beautiful, one of the daughters of the King", a moment of sheer unearthly poetry that verges on psychosis. However, she refuses to accept any new plan and rejects his suggestion that she stay behind, saying she is looking forward to atoning for her sins by her suffering an unjust sentence.Stung by his loss of control over her, he first prays alone, then his face suddenly resolves into a look of predatory lust just before slipping into her room, with the drums implacably beating in the background.The next morning, the fishermen are pulling their nets, and find a dead body in them. It is Davidson, a suicide.The natives first scramble everywhere passing the news, which gets to Dr. McPhail and Horn. They argue as to which of them should go tell Mrs. Davidson.Meantime, Tim has heard the news and comes looking for Sadie. As they approach her door, they hear the jazzy music playing on the Victrola. When they knock at her door and she appears, she is dressed like the old Sadie, net stockings and high heels and full of bracelets. During the night she found out for sure that Davidson was a total hypocrite, so Sadie switched back to her old self. In spite of being shocked at his suicide, she tells Tim she will to go off to Sydney with him to start a new life.As she leaves the hotel with Tim, they come upon Mrs. Davidson, who tells her humbly that she was right about him, after all.