Marlow's first sentence focuses on "the man called Brown." Brown was the terror of the Polynesian islands; he was a well-known, much-feared, immoral pirate who operated off the Australian coast. He did some gun-running, and he robbed and killed and even maimed people for little or no reason. It was also reported that he once kidnapped the young wife of a missionary. He was infamous for his arrogance and for his uncontrollable temper, and he was particularly contemptuous of men who were weak, "quiet and unoffending."
At the height of Jim's fame as the beloved Lord Jim of Patusan, Brown had a run of bad luck. Finally, he was captured by a Spanish patrol. They intended to imprison him, but when they docked at a small Spanish settlement, Brown and his men stole a schooner and headed through the Straits of Macassar. They planned to take the ship to Madagascar, but first, they had to cross the Indian Ocean and, in order to do that, they needed both food and water. Thus, they anchored off the mouth of the river leading to Patusan, hoping to find provisions there.
Brown and fourteen of his crew headed upriver. When they reached Patusan, they were fired upon, but they were able to secure themselves on a knoll about nine hundred yards from Rajah Allang's stockade. They were far from safe, however. As they looked down into the town, they could see the village swarming with "thousands of angry men." Brown was in utter disbelief at the size of the place.
Jim was away when Brown's party was fired upon. He had been away in the interior for over a week, and Dain Waris was in charge. Dain Waris wanted to kill Brown and his men immediately, but the Bugis were not convinced that it was necessary to massacre the white men. It was a decision that Lord Jim would have to make. They trusted only Lord Jim's judgment. Besides, Dain Waris might be killed. In contrast, Jim was the physical incarnation of Truth; he was invincible. Thus, he had to decide what must be done. And so, in Jim's absence, the villagers crowded into his stockade, much like uncertain children waiting for a parent to return home.
Like Dain Waris, Jewel tried to convince the villagers to destroy Brown's band of pirates, but they would not listen to her.
Jewel even had the key to the hut in which five hundred kegs of explosive powder were stored, but no one was willing to initiate such violence. Old Doramin, of course, could have decided the fate of Brown and his men, but he too hesitated; he feared for his son's safety. Nonetheless, he finally ordered that some powder, bullets, and percussion caps be distributed under Jewel's supervision.
Almost immediately, wild and exaggerated rumors began spreading that a large, armed vessel might be moving upriver to aid Brown, so Doramin sent Dain Waris downriver in order to cut off Brown's retreat and to prevent another ship from assisting Brown.
A native called Kassim, a representative of Rajah Allang, arranged for the slimy Cornelius to make contact with Brown's party. Kasumi secretly wanted to take over Patusan, and he knew that he could count on Cornelius to help him by telling Brown about the "unusual," white, Lord Jim who "ruled" Patusan. Jim was a man whom Kassim could not understand; he could not figure out how to take the country from him. Jim was not like the other white men he knew. But Brown was another matter. Brown had a criminal nature, and Kassim could manipulate that kind of man — providing Brown was sufficiently tempted to try and take Patusan by force.
Cornelius, of course, hated Jim, and so he tried to make the possibility of conquest seem as easy as possible. Jim, he told Brown, would be a pushover. Jim was an idealist with no real bravery. The natives had been "captured" by the man's charisma, not by his physical courage. Once Jim was dead, Cornelius vowed, the country would belong to Brown.
Chapters 38 and 39 present more of Gentleman Brown's background, further showing his corruptness, his evil nature, and his amorality. Brown kills for the sake of killing: he is "a blind accomplice to the Dark Powers." What makes Brown so dangerous is the fact that he "was tired of his life and not afraid of death." In fact, Brown would rather be killed than face the possibility of imprisonment. This lack of a fear of death is what makes Brown such a danger to everyone.
It is ironic that Lord Jim is trusted so thoroughly by the people of Patusan that they will not do anything on their own concerning the fate of Gentleman Brown. Even though Dain Waris and Jewel both want the evil man to be killed, the other natives want to wait until Jim's return. Thus, by the very trust that the natives have for Jim, they place Jim in a position of having to make a decision about Brown's life, a decision which will ultimately bring about the deaths of many people, including Dain Waris and Jim himself.
These two chapters also present the other forces aligned against Jim. Kassim is a bitter and evil person who hates without reason, and Cornelius has long despised Jim and has longed for his death because Jim is so perfect and good. Rajah Allang wants Jim dead so that he can return to terrorizing the natives again. Thus, they are all aligned in their treachery against Jim and the forces for good.