Near the end of the nineteenth century, Jim is a young man in his mid-twenties who is the son of a relatively well-off parson in Britain. There’s nothing remarkable about Jim’s early life or physical appearance, but he has big dreams of one day going on adventures and making a name for himself, so he starts training to become a sailor.
Eventually, Jim becomes the first mate of a ship called the Patna, a steamer that has only a few crew members but 800 passengers who are all religious pilgrims, mostly from poor villages. One night, the Patna hits an unseen object in the water. The damage is extensive, and Jim and the skipper believe the ship will soon sink. The skipper and two engineers decide to save themselves by lowering a lifeboat. Jim feels that these men are cowardly and wants to use the crisis to prove himself as a hero. But before Jim knows it, he finds himself almost unconsciously jumping into the lifeboat, right next to the other deserting crew members.
Jim and the fleeing crewmembers believe that the Patna will sink that night, but it doesn’t, and the passengers on board are eventually rescued by some French ships. Jim and the other crew members have committed a serious crime by abandoning ship, but Jim is the only one who stays around to face trial. During Jim’s trial, a man named Captain Marlow takes an interest in Jim, and Jim notices Marlow in the crowd, as well. Jim and Marlow talk and begin a cautious friendship, with Jim sensitive about any potential insult to his honor and Marlow confused by many of Jim’s actions. After a few days of trial, Jim gets a comparatively light sentence: he is stripped of his sailing certifications but is otherwise free to go.
Jim becomes aimless after the trial, having faced the legal consequences of his actions but still feeling haunted by them. With Marlow’s help, he gets a series of low-level jobs where he doesn’t need certifications, but he runs away from them all, often after someone makes a casual reference to the Patna incident. Finally, with the help of Marlow’s associate Stein, a world-famous naturalist and a trader with connections to the black market, Jim gets the opportunity to help run a trading post in a remote village called Patusan.
Jim’s journey to Patusan gets off to a rough start when Rajah Allang, a greedy Malay chief who causes problems for many Patusan locals, particularly the Bugis people led by the elderly Doramin, imprisons him. Eventually, however, Jim manages to escape and form an alliance with Doramin, as well as with Doramin’s son, Dain Waris, who has an interest in Europe and will one day inherit Doramin’s leadership position.
But brash Jim doesn’t stay under Doramin’s protection in Patusan; instead, he seeks out Cornelius, the man who previously worked for Stein but had a falling out with him, and Jim takes on Stein’s former role. Cornelius is conniving and cruel, particularly to his part-Malay stepdaughter. Jim hates seeing how Cornelius treats his stepdaughter. Eventually, he ends up rescuing her and marrying her, calling her by the name of Jewel. Two years after Jim’s arrival in Patusan, Marlow visits and finds that Jim is so well respected by all the locals that they call him “Tuan Jim,” meaning “Lord Jim.” Marlow begins to believe Jim may have finally mastered his fate and come to terms with his past.
One day, however, a notorious captain known as Gentleman Brown ends up near Patusan by chance. Brown recently stole a Spanish ship and is in desperate need of food to continue his journey, and he and his men plan to ransack Patusan for supplies. Jim is away at the time, but Dain Waris and other local warriors manage to wound some of the invaders. Without Jim’s leadership, the villagers of Patusan can’t agree on finishing off Brown’s men, and so they all remain for a while in a stalemate.
When Jim gets back, Brown sees an opportunity to take revenge on Jim for how the Bugis warriors attacked his men. The double-crossing Cornelius is also looking for revenge on Jim and is eager to help Brown. Brown leads Jim to believe that his men just want peaceful safe passage back to the ocean so that they can leave Patusan for good. Jim agrees with this plan and orders Dain Waris and the others not to attack them. As Brown is leaving, however, he sneaks up on Dain Waris and his men and fires several rounds, for no reason other than to send a message. Dain Waris dies, along with many others.
Doramin is devastated when he learns that his son, Dain Waris, is dead and that Jim was the one who gave the order to let Brown walk free. Jim himself feels extremely guilty—when Jewel tells him that he must be prepared to flee the village or to fight for his life, Jim instead resigns himself to going to Doramin to face judgment for his actions. A grief-stricken Doramin pulls out a gun and shoots Jim in the chest, killing him instantly.
Jewel eventually ends up with Stein, who grows old and begins to prepare to die in his house full of butterfly specimens from his days as a naturalist. Marlow learns about Jim’s fate one day when he visits Stein’s house.