The line 'It was now deep dusk in the forest, and deepest in that part of it where these two were journeying' foreshadows the identities of the two men.
In the passage, the line that foreshadows the identities of the two men is the following:
It was now deep dusk in the forest, and deepest in that part of it where these two were journeying.
This line foreshadows the identities of the two men by establishing the setting and the time of day, creating an atmosphere of mystery and anticipation.
The use of the word 'deepest' suggests that the forest represents a symbolic journey into the depths of human nature, where the true identities of the men may be revealed.