OT III returns self determinism and freedom from overwhelm. Its subject matter is a pan-racial engram which in Ron's Journal 67 he said occurred on this planet approximately 75 million years ago. While some scoff at the details of the story, the point is moot. No one needs to "believe" the story. One is simply required to audit the level, which invariably results in tremendous resurgence in self determinism and FREEDOM FROM OVERWHELM. In Scientology, the only standard of value is the acid test of workability. OT III produces a specific definite result.
This level requires one be properly set up with all earlier grades having been run to their full end result. One also most be a good auditor. it is not a short level and like everything in Scientology speed of progress is of no real value. All that matters is the result and that can take some dedicated perseverance.
People moving through this level change markedly. This is where one really transitions from focus on the material aspects of self, to a full spiritual beingness.