The story of Xenu is covered in OT III, part of Scientology's secret "Advanced Technology" doctrines taught only to advanced members who have undergone many expensive hours of auditing and reached the state of Clear.[9][13] It is described in more detail in the accompanying confidential "Assists" lecture of October 3, 1968 and is dramatized in Revolt in the Stars (a screenplay written by L. Ron Hubbard in 1977).[9][16]
Hubbard wrote that Xenu was the ruler of a Galactic Confederacy 75 million years ago, which consisted of 26 stars and 76 planets including Earth, which was then known as "Teegeeack".[5][10][17] The planets were overpopulated, with an average population of 178 billion.[1][4][6] The Galactic Confederacy's civilization was comparable to our own, with aliens "walking around in clothes which looked very remarkably like the clothes they wear this very minute" and using cars, trains and boats looking exactly the same as those "circa 1950, 1960" on Earth.[18]
Xenu was about to be deposed from power, so he devised a plot to eliminate the excess population from his dominions. With the assistance of psychiatrists, he summoned billions[4][5] of his citizens together under the pretense of income tax inspections, then paralyzed them and froze them in a mixture of alcohol and glycol to capture their souls. The kidnapped populace was loaded into spacecraft for transport to the site of extermination, the planet of Teegeeack (Earth).[5] The appearance of these spacecraft would later be subconsciously expressed in the design of the Douglas DC-8, the only difference being: "the DC8 had fans, propellers on it and the space plane didn't".[15] When they had reached Teegeeack/Earth, the paralyzed citizens were unloaded around the bases of volcanoes across the planet.[5][10] Hydrogen bombs were then lowered into the volcanoes and detonated simultaneously.[10] Only a few aliens' physical bodies survived. Hubbard described the scene in his film script, Revolt in the Stars:
Simultaneously, the planted charges erupted. Atomic blasts ballooned from the craters of Loa, Vesuvius, Shasta, Washington, Fujiyama, Etna, and many, many others. Arching higher and higher, up and outwards, towering clouds mushroomed, shot through with flashes of flame, waste and fission. Great winds raced tumultuously across the face of Earth, spreading tales of destruction...

– L. Ron Hubbard, Revolt in the Stars[9]