Sixth Column, also known under the title The Day After Tomorrow, is a science fiction novel by Robert A. Heinlein, based on a story by editor John W. Campbell, and set in a United States that has been conquered by the PanAsians, a combination of Chinese and Japanese. Originally published as a serial in Astounding Science Fiction (January, February, March 1941, as by Anson MacDonald) it was published in hardcover in 1949.
Read more about Sixth Column: Plot Summary, Background, Reception, Portrayal of Racism