Heart of Darkness is a novella by Polish novelist Joseph Conrad, about a voyage up the Congo River into the Congo Free State, in the heart of Africa, by the story's narrator Marlow. Marlow tells his story to friends aboard a boat anchored on the River Thames, London, England.
This setting provides the frame for Marlow's story of his obsession with the ivory trader Kurtz, which enables Conrad to create a parallel between London and Africa as places of darkness.