My best friend in high school wasn't allowed to attend sex-education classes. Her fanatically Christian family strictly prohibited it, and she was relegated to the gym while the rest of us gaped at Nova's The Miracle of Life, not in wonderment but in horror at how they fit those little cameras up the pee holes of those poor suckers. When we returned to the gym, my friend would ask what we learned that day, and "We watched a video from the inside of the human body" didn't really sound that cool. The recounted session had to be worth her while, so we embellished: "Yeah, we watched this show where people were totally doing it, and they would, like, show the guy's penis going into her twat and then you could see the stuff come out—it was like Endless Summer II!" I don't remember why we referenced Endless Summer, but we sold the story. Our motives—like Debbie Nathan's in her new-in-paperback book Sybil Exposed—were quite pure, even if our delivery was a bit jazzed up for effect.

A good sell can turn the stinkiest turd of a story into a sparkly moneymaker. Although based on a series of exaggerations about a fairly banal mental-health case study, Flora Schreiber's 1973 book Sybil contained all the grotesque ingredients of the modern blockbuster: violence, sex, victimization, betrayal, and human suffering. People are invariably attracted to misery, and Sybil gave this misery a name: multiple personality disorder. Bringing multiple personality disorder into the public sphere granted an identity to the emotional conflicts of millions of men and women. Real or imagined, the public empathized with Sybil's story.

Sybil Exposed is Nathan's not-awful attempt to discredit the "facts" at the foundation of the Sybil phenomenon. The 1973 book was loosely based on the life of psychiatric patient Shirley Mason. Her accounts of horrendous childhood abuse and the resulting multiple personality disorder diagnosis exploded onto literary and academic circuits, and the silver screen (twice!). And it ushered multiple personality disorder into popular culture. Sybil is a cultural icon ripe for a proper debunking, and Nathan deconstructs it with an equal amount of reliable sources and colorful conjecture.

The primary mission of Sybil Exposed is to discredit its key players: Mason, her psychiatrist Dr. Cornelia Wilbur, and Sybil author Schreiber. And rightly so—it's obvious from Nathan's interpretations of quoted letters and audiotaped psychotherapy sessions that the bulk of Schreiber's text was a loose interpretation of Wilbur's treatment notes, which in turn were based on the very questionable presence of Mason's multiple personalities. Given the lingering effect of Sybil's influence over generations of multiple personality disorder patients, Nathan's exposé is an important one, but her story reads more like a hard-boiled detective narrative than a respectable piece of investigative journalism.

Nathan had access to the necessary ingredients for a solid exposé, including letters from Mason buried for years at the John Jay College of Criminal Justice and interviews with living acquaintances. It seems to me the letters reveal that Wilbur, Mason, and Schreiber consciously manipulated Mason's personal issues to create a supremely successful empire. It cannot be denied that this was a shitty thing to do to an empathetic public. However, Nathan forces the issue into more than 200 pages of text, gluing together her hypotheses with a clever amalgamation of conjecture. Addressing a period in Mason's adult life when she spent a great deal of time playing with baby dolls and writing greeting cards to her psychiatrist, Nathan writes: "[Mason] signed the cards, 'Shirley, Inc.' hoping against hope for their literary and marketing success" (emphasis mine). True, these activities are not those of a typically functioning grown-up, but Nathan reaches beyond the substantive and claims to know the inner thoughts of a long-dead Mason.

It would be smarter to let Mason stay dead and discredit the foundations of Sybil's diagnosis in a tidy little Variety article on the grisly horrors of pop medicine. Instead, Nathan questions the validity of an entire religion in order to demonstrate the negative effects of Mason's Seventh-day Adventist upbringing on her concepts of normality. Yes, this religion is weird. But to introduce the theme by describing the 19th-century founder of the church as a "barely educated farmer named William Miller"? Right. Unlike all those other religions founded by Harvard alumni. Nathan takes these weak shots at a potentially strong thesis—ostensibly to pad her story—and in the effort to create a hardcore exposé, she produces a silly, tabloidish version of the truth.

Just as Sybil was built on the shifting sands of ambition and manipulation, so is Sybil Exposed. Nathan's exposé could have been a valuable investigation into a fad that had lasting impacts on thousands of lives. It could have done its job with class and finesse. Instead—like Sybil—it's a floppy rendition of what might have happened, and when we're talking about a very real player in the field of mental health, that's simply not enough.