Xenu kingpin family member to TELL ALL in shocking new book that rips the lid off the controversial cult founded by sci-fi hack L. RON HUBBARD!

Yes, celebs like Tom Cruise. Kirstie Alley  and John Travolta belong to the Church of Scientology but don’t expect them to dish the inside deets.

Instead, Scientology leader David Miscavige’s niece,  Jenna Miscavige Hill, a frequent critic, has cut a deal with HarperCollins imprint William Morrow for her memoir "Beyond Belief: My Secret Life inside Scientology and My Harrowing Escape”.

Hill, 28, according to the presser  will reveal "strange and disturbing" details about growing up Xenu providing a firsthand account of Scientology's "upper ranks."

Her uncle, the controversial David Miscavige oversees the church, founded in the 1950s by sci-fi writer L. Ron Hubbard who before founding the org was best known for his lurid pulp tales of “Battlefield Earth” later made into a film starring a dreadlocked Travolta.

It has long been rumored that Hubbard established the church as a wager with Astounding magazine editor John W. Campbell who wrote the oft- filmed novella "Who Goes There?" aka “The Thing (From Another World)".

Campbell is said to have told Hubbard to start his own church as a way to beat the IRS.