Lord Jim follows a young Englishman who goes to sea full of heroic daydreams drawn from cheap adventure books. He is competent and well liked, working as a water-clerk in Eastern ports, but he carries a secret. The novel slowly reveals it, then circles it again and again from different angles, refusing a single clean account.
The secret is the Patna. Jim serves as chief mate on an old steamer carrying eight hundred Muslim pilgrims when it strikes something in the dark and seems certain to founder. In a moment he cannot fully explain, he leaps overboard with the panicking captain and crew, abandoning the sleeping passengers. The ship does not sink. It is towed in, the pilgrims survive, and Jim must face an official inquiry that strips him of his certificate.
Much of the story is told by Marlow, an older sea captain who meets Jim at the trial and cannot let him go. Marlow is drawn to Jim precisely because Jim is one of us: not a hardened villain but an ordinary young man whose ideal of himself collapsed under a single test. Through Marlow's long, doubling narration the book examines guilt, the gap between intention and act, and how far anyone can be sure they would have stood firm.
Unable to bear the shame, Jim drifts from port to port, quitting any job where the Patna is mentioned. Stein, an old merchant and naturalist, diagnoses him as a romantic who cannot make his dream come true, and offers a remote solution: a trading post deep in Patusan, a district cut off from the world. There Jim is given a clean field with no past.
In Patusan, Jim earns real authority. He settles a local war, gains the trust of the chief Doramin and his son Dain Waris, takes the woman called Jewel as his love, and becomes Tuan Jim. The second life seems to redeem the first, until the marauder Gentleman Brown arrives. Jim's choice to let Brown go free leads to Dain Waris's death, and Jim walks unarmed to Doramin and accepts the bullet. He dies answering for the failure he could never quite leave behind.