I was curious (and bored) so I did a quick web search. I found this link:
http://www.lermanet2.com/exit/volcanos.html
Which has this to say about Scientology:
1.3: "Section III OT" summarised
OT3 is a secret, senior level within Scientology that can only be done after many other courses, by which time the client is well prepared, well behaved and ready to, if not believe, at least work with anything Hubbard says as being truth, ignoring all evidence to the contrary. People are not suckers to have been conditioned in this way, but have been ushered through many successive plausible small steps and changes, each one acceptable by itself, but progressing towards enchantment with past life recalls, a shut-down of critical thoughts, alienation from outside opinion and a turning-towards and eventual unquestioning acceptance of Hubbard's imposed belief system.
OT stands for "Operating Thetan" where "thetan" is Scientology jargon for "soul", and "Operating" is supposed to mean "At cause over life, thought, matter, energy, space and time". The 3 means that this is the third in the series of courses.
OT3 mainly concerns a supposed "Incident II" happening 75 Million years ago, when Xenu an officer in charge of the 76 local planets of the "Galactic Confederation", solved overpopulation by mass exterminations, mostly by shootings. The souls of those killed were collected together using super cold, transported to volcanoes on earth (he gives a list of these and they are checked out in this paper), H-bombed at the volcanoes, collected up again using electronic ribbons and transported to Hawaii or Las Palmas. They were there subjected to 36 days of hypnotic "implants" using films and simple apparatus, which in their already shocked state was supposedly very effective and kept them clustered together and trapped on earth as demons.
We are each supposed to contain large numbers of these traumatised and grouped souls stuck around our bodies like some sort of spiritual "fleas" (Hubbard's term). The OT3 processing consists of beaming a narrowly focussed attention onto clusters of souls to communicate with and separate them, then get individual souls to recall the volcano they were blown up at etc. which by Dianetics theory releases them from the trauma. If the souls resist recalling the "Incident II" killings, bombings and hypnosis, then "Incident 1" is supposed to be offered for recall instead.
"Incident I" is time-stamped at 4 quadrillion years ago, and here I quote in full: " LOUD SNAP WAVES OF LIGHT CHARIOT COMES OUT, TURNS RIGHT AND LEFT CHERUB COMES OUT BLOWS HORN, COMES CLOSE SHATTERING SERIES OF SNAPS CHERUB FADES BACK (RETREATS) BLACKNESS DUMPED ON THETAN" (Thetan = soul = spiritual "flea" = "demon").
If even "Incident I" won't work, then the Scientologist is doing something wrong and his Dianetics procedures are checked-over. If even then the Scientologist fails to get results, he is condemned as having lied about completing previous courses and required to do the entire series of over 20 courses and counselling from beginning Scientologist onwards all over again.
The end result of OT3 is variously declared to be "freedom from overwhelm", also "No Body thetans left".