The series begins at the onset of a civil war between the United Earth Forces (UEF) and the Colonization Industrial Companies (CIC), which comprises the various outposts and colonies beginning at the planet Saturn and beyond.[1] The civil war begins when it is discovered that an immense black wall appears near Saturn, cutting the Solar System in two. The black wall absorbs all light and matter. Enormous, incomprehensible and terrifying, "the wall" is centered on Uranus's moon Oberon, cutting off access to any planet beyond Saturn. Admiral Von Richtburg discovers that the CIC was attempting to begin a civil war, and orders the Purgatory Squadron, a band of soldiers given a second chance after courts-martial, to investigate the phenomenon known as "the wall".[1]

After the Purgatory Squadron devises a method of breaching and investigating the wall, they are fired upon by a vessel of unknown design.[1] Admiral von Richtburg orders his UEF 3rd Fleet into the wall, and thus begins the First Universal War.