Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third-Person Omniscient
The narrative weaves in and out of characters' minds seamlessly, often floating back and forth between different people and even different locations within a chapter.
The narrator doesn't really editorialize on what the characters are doing or saying; rather, s/he lets quotes do the talking and/or uses free indirect discourse to show us what characters are thinking.
For an example, let's look at how the narrator presents contradictions in Nostromo's thoughts when he meets up with the doctor after hiding the silver on the Great Isabel. Nostromo initially acts super annoyed that he's going to have to deal with the doctor's curiosity about the silver:
Leaning back with folded arms at the foot of the immense building, he dropped his head, biting his lips slightly, and not looking at the doctor. "Now," he thought to himself, "he will begin asking me about the treasure." (III.9.41)
Just a few lines later, however, Conrad uses free indirect discourse to show us that Nostromo is now annoyed that the doctor hasn't asked: "…he had never even asked after it. Not a word of inquiry about the most desperate undertaking of his life" (III.9.49).
As you can see, Nostromo is definitely flip-flopping here, and the narrator doesn't call him on it or draw attention to it. Instead, s/he just presents what the characters are thinking/saying, contradictions and all, without commenting. So, it's up to you to catch when characters are fibbing or being inconsistent—and you don't even have a lie detector.