Joseph Conrad's Heart of Darkness retells the story of Marlow's job as an ivory transporter down the Congo. Through his journey, Marlow develops an intense interest in investigating Kurtz, an ivory-procurement agent, and Marlow is shocked upon seeing what the European traders have done to the natives. Joseph Conrad's exploration of the darkness potentially inherent in all human hearts inspired the 1979 film, Apocalypse Now , although the setting was moved to Vietnam.