Like a knight of the Round Table, Marlow sets off in search of strange adventures. He only gradually acquires a grail, as he picks up more and more hints about Kurtz. Like a knight he is frequently tested by signs he must confront, question and interpret. Signs are things you see or experience or are told which have meaning beyond the literal: old women knitting black wool might simply be relatives of the company personnel given some position of respect and usefulness, or the somber color of their wool and clothing, and their serious demeanor, might suggest that they mind the gateway to a mysterious underworld. You might take as signs the following:

• The Inner Station, with it's barrels of unused rivet, its needless blasting of a cliff as a railroad is built, its valley of death and shackled prisoners, and its gleaming white-suited Accountant, who frets over his figures while a man lies groaning his last in his office.
• The Central Station, rivetless and strawless, where the manager smiled his mysterious mean smile and the idle brickmaker (the "paper-mache Mephistopheles") drinks champagne and lights his privileged candle in its silver holder, where a man is dragged out a random and beaten for having set a fire (regardless of whether he did), and where Marlow's boat is sunk (meanwhile, the Eldorado expedition passes through- this section provides the most detail of Marlow's increasing fascination with the enigmatic Kurtz.)
• The Russian's cabin, then the Russian himself, a Shakespearean Fool with his motley clothes, his icon which is dull text (language pored over reverently in spite of content), and his ambivalent relationship with Kurtz.
• The "gateposts" which become heads on poles, shrunken and dried and made to face Kurtz's house: signs not of domestic order but of terror.

Even before he sets out, omens present themselves to Marlow; old women knitting black wool in the Belgian office, the phrenologist measuring Marlow's skull and warning of changes to take place inside, the tale of how his predecessor died in an uncharacteristic dispute over black hens.