That we are aliens , and a war was fought thousands of years ago and the losers were dumped in big holes in the earth and trapped by alien technology but something went wrong and that we must pay many thousands of dollars to find out how to resolve it all.
In short : complete nonsense.
If you want to inform yourself of more type in a ' Ex-Scientologist ' in a search engine, There are many stories out there of people who got caught up in it and will serve to inform you better than I could in here.