Tania Head’s 9/11 story was beyond harrowing. She was in the World Trade Center when the plane dove into the building. Dazed and sickened, she walked down 78 floors with her skin on fire and her right arm dangling. She survived, but her husband died at Ground Zero that day, and the horrific sights she saw on her crawl to safety plunged her into a haunted depression. Only through her involvement as a founding member of the World Trade Center Survivors’ Network did she conquer her grief and trauma.

There was a little problem, though. Tania’s name isn’t really Tania; it’s Alicia. Her husband didn’t die in the towers, because she wasn’t married. Someone named Dave died, and she said he was her husband, but in fact she had never met him. She didn’t hold a high-powered job at Merrill Lynch, as she claimed. She wasn’t at the World Trade Center on 9/11. In fact, she wasn’t even in the country. She was in Barcelona.

This epic lie is the subject of “The Woman Who Wasn’t There.” One of the co-authors, Angelo J. Guglielmo Jr., was involved in the WTC Survivors’ Network and considered Head a close friend. He is also the director of a documentary by the same title, which debuted April 17 on the Investigation Discovery network.

It’s easy to understand why survivors were taken in by Head’s story. The level of detail is breathtaking. Over and over, to rapt audiences, Head mourned the young man wearing a red bandana who stretched out his hand to help her to safety, only to disappear into the smoke to die a hero. She never told anyone her husband’s last name (to protect his parents’ privacy, she insisted), and sometimes she seemed to slip up and call him her fiance, but again and again, she’d recount the poignant story of their wedding in Hawaii. When she visited Dave’s name at the memorial, she liked to bring a toy yellow taxi, as a memento of their charmed first meeting, to place near the reflecting pool. Who would make all that up?

The depth of the deception is even more puzzling given how very public a face of the survivors’ movement Tania Head became. It was Head, as one of the first docents at Ground Zero, who walked Mayor Michael Bloomberg and other luminaries around the site. “She was the ubersurvivor,” Fisher and Guglielmo write. As the survivor with “the saddest [story] of them all,” she gained celebrity status. An enterprising New York Times reporter, David W. Dunlap, eventually demanded answers about inconsistencies in her story and exposed her. Rather than expressing remorse, Head became angry and defiant, claiming that her fellow survivors had betrayed her by believing the reporter.

’The Woman Who Wasn't There: The True Story of an Incredible Deception’ by Robin Gaby Fisher & Angelo Guglielmo (Touchstone)

So why did she do it?

That is obviously the most enticing question. Unfortunately, the authors don’t provide an answer. Although Guglielmo and Head were intimate for years, and it was she who encouraged him to begin a documentary about the survivors, she would not open up to him about the truth once the deception was uncovered. He was able to track down a childhood friend from Barcelona who told him about some of Head’s traumas: She had a bad car accident at 18 in which her arm was indeed severed (if we believe the account), and her father did prison time for embezzlement. “It is around that time, after those life-changing events, and especially after her family unit fractured following her parents’ contentious divorce, that Alicia started living in make-believe worlds.”

Although the authors aren’t Head’s psychiatrists, a little more background on the psychology of pathological lying, also known as pseudologia fantastica, would have been useful. Are the spinners of complex imaginary worlds always so hard to spot? The book contains no information on other spectacular hoaxes (Robin Hemley’s “Invented Eden: The Elusive, Disputed History of the Tasaday” comes to mind), nor reference to any books, such as Lauren Slater’s “Lying: A Metaphorical Memoir,” that attempt to penetrate the mind-set of the compulsive liar. Such context could help flesh out a tale about a character whose motivation remains shadowy.

We know that Head’s a liar from the flap copy, but the book doesn’t reveal the deception until very late. Structurally, that gives the authors a problem: a lot of pages to fill and not a lot of suspense. For this reason, the documentary might prove a more intriguing form for the material than the written account. It will be fascinating to be able to watch Head lie in real time — and see if we’re as taken in by her performance as almost everyone else appeared to be.

bookworld@washpost.com

Lisa Zeidner is the author of four novels and a book of nonfiction. Her new novel, “Love Bomb,” is forthcoming.