Louis Theroux versus the Church of Scientology. It’s a near-irresistible contest: the very face of deadpan scepticism, up against that many-headed hydra of indecipherable rage.

My Scientology Movie is the second documentary on the subject in recent months, following Alex Gibney’s more thorough and methodical Going Clear. Where Gibney circled the movement right from its beginnings, seeking to analyse its methods and impugn its motives, Theroux just gets right in there and jabs it in the ribs, that imperturbable mask of irony driving its partisans even more bananas than usual.

An unpunctuated “Don’t go there big man” is among the messages Theroux received from caution-advising Twitter followers, on announcing his intention to investigate Scientology for this BBC-financed doc. Another warns him that “the crazies” will soon be out in force against him, as indeed they are.