I. Departure:
A. The Call to Adventure
Marlow's aunt pulls some strings and gets him a job with "The Company" in Africa. One may consider this adventure, or consider it a career of the colonial era. His life does change i'd daresay. This compares him with heroes.
B. Refusal of the Call
Marlow does not refuse the call. He takes it as soon as it rings at him. This is one thing that contrasts him with heroes.
C. Supernatural Aid
Once Marlow has accepted his job he does not receive supernatural aid. Why should he if he is not in the need of any help? He is perfectly fine as he is. The examinations he took say the same. This is another thing that contrasts him with heroes.
D. The Crossing of the First Threshold
Once he gets on the steamer from his aunts place and sets out on his journey to Africa he begins crossing the threshold of the world he knows, to the world that no one knows. He begins to cross over to the dark
E. The Belly of the Whale
Once he is dropped of at his first stop Marlow realizes how where he is at is so different from home. So much so that once he see's someone that reminds him of home, he takes his time staring with his mouth wide open at the most beautiful being he has ever seen with clean clothing, cuffs, and collars. Then he notices the African slaves again. It finally settles in him that he will not be going home for a while. A long while. This compares him with heroes.
II. Initiation
A. The Road of Trials
Marlow begins his journey. He travels with a caravan to a station where he finds out his ship has been wrecked. Then he travels on after he fixes his ship to Kurtz, the greatest man eva'. On the way to Kurtz, Marlow encounters things that seem to slow him down. Mainly natives that attack them, but a blow of the ships horn by Marlow saved the day. This is another way he compares to heroes.
B. Meeting with the Goddess
For Marlow I believe that there is no goddess that he meets. The point of his "adventure" was to meet Kurtz and see the man behind the mystery. In this way he compares with heroes.
C. Woman as the Temptress
I believe that Marlow did not have temptations. He was a very weird man, but then again he is also narrating the story so we cant trust his words 100%. The only thing that seems to tempt him is the thought of Kurtz and mystery of the man. He is tempted by his legacy, thoughts, words, etc. This is what compares him with heroes.
D. Atonement with the Father
This is when Marlow finally meets with Kurtz. This part of the "journey" lasts until the death of Kurtz on the steamship. Throughout the time Marlow and Kurtz spend a lot of time together. Marlow receives that which he has been wanting since he first heard of Kurtz. Then Kurtz dies, "Mistah Kurtz - He dead." This compares him with heroes.
E. Apotheosis
One can say that Kurtz's death is deified by his legacy (except in the eyes of the Manager), but then again one can also say that only someone who understood Kurtz, like Marlow, could deify him. This compares him with heroes.
F. The Ultimate Boon
Marlow is entrusted by Kurtz all his thought, belongings, and works. This includes his pamphlets, letters, and a picture of his "Intended" fiancee. This compares him with heroes.
III. Return
A. Refusal of the Return
Marlow does not refuse to return. He gets ill and does his best to get home as fast as he can. This contrasts him with heroes.
B. The Magic Flight
This part is when Marlow though severely ill, does his best to return home. In the end he finally makes it home with all the things entrusted to him by Kurtz.This compares him with heroes.
C. Rescue from Without
Once he is home, Marlow's aunt brings him back to tip top shape. Then Marlow begins to spread Kurtz's word in the ways he see's fit. Though sometimes it takes a bit of convincing to get the things from him. This compares him with heroes slightly as well.
D. The Crossing of the Return Threshold
When he is home, Marlow slowly begins to despise the people and their egotistic lives. This compares him with heroes slightly, but in a bit of an oddly negative way.
E. The Master of the Two Worlds
Marlow seems to skip this part. As mentioned above, he begins to despise the people slightly. Besides that he just rolls with the times, if that's a way of saying it. This both compares and contrasts him with heroes.
F. Freedom to Live
One can assume that Marlow has acheived the "freedom to live" since he is in fact telling a story of his past. This compares him with heroes.
So we can conclude that Marlow's story does follow the steps of "The Hero's Journey." However, since this is a story of a colonial time period, it does stray on several points. One must delve into the story to figure out comparisons that link to "The Hero's Journey." Even though Marlow may not be a hero, Joseph Conrad writes along the lines of a "Hero's Journey."