Ok, back to OT 3. On this level, you are told about Xenu the evil war
Lord who supposedly 75 million years ago, due to over population, killed
tons of people. (See Scientology+South Park to see an illustrated excellent view of the whole story).
Ok, so in session, you're supposed to contact and get rid of "Body Thetans". Thetan in Scientology is = spirit. Body thetans (BTs) are
these dead space aliens killed by Xenu, and then end up (supposedly--
not really) glued on us, and THAT is the true source of all of your problems! HA!
So this is "Solo auditing" --where you're supposed to go into session, contact these beings, run this little process Hubbard wrote, and then they leave. Ultimately on OT 3, supposedly, you get rid of ALL of them, and then you're done.
Of course after you finish, whatever you *thought* you fixed comes back (as it doesn't really work). At this time, you're then sold the next level.
It's one more train of mind control. And it's VERY VERY Expensive, too.
Hope that adds a bit more.