In Joseph Conrad's Heart of Darkness, each station at which the protagonist, Marlow, stops has something important or puzzling.
In the first station, the Outer Station, when Marlow arrives, he sees Africa as it has become with the interference of the white man and his ferocious desire for more ivory. He sees the “deathlike indifference of unhappy savages.” A cliff is being blown-up for no good reason. It is not in the way. Machinery lies about unused and rusting away. The whites are particularly vicious with their "slaves." Many are diseased and starving to death.
Marlow meets the company's accountant at this location.
In less than two weeks, Marlow departs with about sixty men, all headed for the Central Station, their next stop. Here Marlow finds that someone has foolishly driven his boat (which is to carry him to the Inner Station) onto the rock bottom of the river that has ripped out its hull; this will probably take two months to fix. (It is underwater.) Marlow tries to get supplies (rivets), but for many weeks, the supplies mysteriously do not arrive even though they have been repeatedly ordered.
It is here that Marlow meets the manager and his uncle (who feel threatened by Kurtz), as well as a brickmaker who seems to make no bricks, and an engineer who is willing to help Marlow. Other groups visit the location, pilgrims pass through, and also:
...[a]n exploring party, the Eldorado Exploring Expedition...For the next six weeks, they appear in sections. A white man on a donkey leads each group, followed by a band of blacks. They are reckless, greedy, and cruel. They will “tear treasure out of the bowels of the land.” (e-Notes Summary/Analysis)
The last station, the Inner Station, is where Marlow will find Kurtz. But this place is full of insanity and death. Civilization has reached here even though Kurtz, a Company man, has lived with the natives for sometime. Kurtz is unwell, and seemingly mad. Around his hut there are stakes with human heads on them. It seems there have been instances of human sacrifice. The natives worship Kurtz and do now want him to leave. This then, is the heart of darkness, not only found within Kurtz, but in the center of the jungle which is a place of mystery and the unknown.
Each station has something different to teach Marlow, and secrets that are closely kept.