The name of what novella fills in the blank?
" Apocalypse Now is a 1979 American epic war film ... loosely based on the 1899 novella ____________ ... The setting was changed from late 19th-century Congo to the Vietnam War."
"In 1998, the Modern Library ranked [it] 67th on their list of the 100 best novels in English of the twentieth century," even though it came out in the 19th century.
Heart of Darkness