Milton L. Humason never received a formal education past the eighth grade, and yet became one of the worlds most influential astronomers. With a love for the outdoors, Humason became a “mule skinner” whose job it was to take equipment up to the Mount Wilson Observatory as it was being built. This Wild Abyss tells the story of Milton who forms an unlikely friendship with world-renowned astronomer Edwin Hubble and assists him at Mt. Wilson Observatory in the 1920s, leading to the discovery that the universe is expanding.