When BBC reporter John Sweeney last investigated the Church of Scientology three years ago, he was spied on by sinister strangers and condemned as a bigot by the church’s leaders.  Now, as Sweeney returns to investigate the church again, one of the officials has turned whistleblower to help him reveal its dark secrets. The Secrets of Scientology tells the story of what was going on behind the scenes back then - and what is happening now.