avid Kittredge gives us a thoroughly enjoyable, detailed account of the catastrophe that was John Boorman's 1977 film Exorcist II: The Heretic, the deeply ill-conceived and widely derided follow-up to The Exorcist, a bizarre but ambitious fantasy supernatural rhapsody, brimming with unintentional comedy. Yet it was visually bold and even brilliant, pioneering in its use of Steadicam; Linda Blair and Max von Sydow were persuaded to return; Richard Burton was cast as a troubled priest, and Louise Fletcher as a psychiatrist whose weird "mind-reader" contraption was entirely ridiculous. At the first film, people screamed. Now they screamed with laughter.

According to an apocryphal tale gleefully repeated by William Friedkin, director of the first film, the sequel resulted in an enraged audience one night turning round and booing Warner Brothers executives in the back row of the cinema, and then chasing them out of the building and down the street. Boorman desperately recut the film with the sillier bits removed. But the damage was done.

Boorman is interviewed here and generously goes into great detail about his painful and mortifying experience with the film, how he had originally been offered the first Exorcist, disliked the story and turned it down, but was induced to take on the sequel. Perhaps Kittredge could have made it clearer how risky it was for Boorman to have taken on a project which he fundamentally didn't believe in and was somehow creatively working against. He hired a kind of script-and-direction consultant, his friend Rospo Pallenberg, whose influence with Boorman annoyed the cast.

This, after all, was the era of sequels, and Coppola's Godfather II had shown that they could be as good or better than the original. It was also an era when brilliant directors were trusted by studios to follow their instincts, cushioned from risk by something called "blind bidding" from movie theatre chains who would pay upfront for films on the basis of known quantities like stars, story and director, a practice which this disastrous film ended. But it was also an era when, after Mel Brooks's The Producers, the media's chattering classes were alive to the hilarity of so-bad-it's-good. There was something else, too, something rarely acknowledged by reviewers: the pressure to follow extravagant praise with disparagement, so that the critical-superlative economy does not go bankrupt. And finally, like William Friedkin's Sorcerer that same year, like all films good and bad of the time, Exorcist II: The Heretic had to go up against Star Wars, which blew everything else out of the water.

It's another proof of William Goldman's maxim that nobody knows anything. If people had laughed at the spinning head in the first Exorcist, industry sages would have shrugged and said: yes, of course, obviously, it's absurd. But the stars were aligned for that one. Now in retrospect we can make a case for Exorcist II: The Heretic being an interesting and misunderstood film. Kittredge quotes some mean reviews but doesn't mention that the New Yorker's Pauline Kael actually made a contrarian case for it at the time, on the basis of its delirious experimental visuals. Perhaps the truth is that Heretic was, like Boorman's sci-fi adventure Zardoz with Sean Connery in the crazy red mankini: weird, surreal, challenging, a shapeshifting creature vulnerable to mockery, at once monstrous and terribly fragile.