The Gods Hate Kansas, by Joseph J. Millard (epub/Kindle/pdf)
The aliens' invasion began with meteor strikes in Kansas. When the investigating team disappears, it signals the start of a strange invasion of Earth. At first, a number of humans are enslaved and forced to build a rocket aimed at the stars. Then comes the Crimson Plague, which sweeps across the Earth's population, ravaging the civilized world. Among the few who escape is astrophysicist Curt Temple, whose girlfriend, Lee Mason, is among the enslaved. Curt must pit his slim knowledge against the most perfect intelligence in the cosmos to save the world--and the woman he loves!
A classic science fiction novel, originally published in the November, 1941 issue of Startling Stories magazine!