Sixth Column, also known under the title The Day After Tomorrow, is a science fiction novel by American writer Robert A. Heinlein, based on a then-unpublished story by editor John W. Campbell, and set in a United States that has been conquered by the PanAsians, who are asserted to be neither Japanese nor Chinese. Originally published as a serial in Astounding Science Fiction (January, February, March 1941, using the pen name Anson MacDonald) it was published in hardcover in 1949. It is most known for its race-based premise. Plot summary A top secret research facility hidden in the Colorado mountains is the last remaining outpost of the United States Army after its defeat by the PanAsians. The conquerors had absorbed the Soviets after being attacked by them and had then gone on to absorb India as well. The invaders are ruthless and cruel. As an example, they crush an abortive rebellion by killing 150,000 American civilians as punishment. Noting that the invaders have allowed the free practice of religion (the better to pacify their slaves), the Americans set up their own church in order to build a resistance movement – a "sixth column", as opposed to a traitorous fifth column. The laboratory is in turmoil as the novel begins. All but six of the personnel have died suddenly, due to unknown forces released by an experiment operating within the newly discovered magneto-gravitic or electro-gravitic spectra. The surviving scientists soon learn that they can selectively kill people by releasing the internal pressure of their cell membranes, among other things. Using this discovery, they construct a race-selective weapon that will stun or kill only Asians. Background The idea for the story of Sixth Column was proposed by John W. Campbell, who had written a similar unpublished story called "All". Heinlein would later write that he "had to reslant it to remove racist aspects of the original story line" and he would also have to write that he did not "consider it to be an artistic success." Heinlein's work on Campbell's "All" was considerably more than just a re-slanting; Campbell's story was felt to be unpublishable as it stood, written in a pseudo-archaic dialect (sometimes inconsistently), and provided no scientific explanations for miraculous powers of the American super-weapons, which the PanAsians have no explanation for other than to conclude that weapons' powers must be divine. Science fiction writer-critic George Zebrowski believed that Heinlein