By Melissa Maerz
November 05, 2014 at 05:00 AM EST

Wonder Woman used to be a warrior princess. Now she’s often just a pretty girl. When director Zack Snyder released an image of Gal Gadot as the Amazonian princess in the upcoming Batman v Superman: Dawn of Justice, one critic quipped, ”During production, we had to ask ourselves so many tough questions. Like, for instance, which size zero bikini model is best suited to play this strapping superhuman?” Only a few years ago, David E. Kelley wrote a Wonder Woman pilot that found the freedom fighter crying over a boy while eating ice cream. So it’s all the more fascinating to learn from New Yorker writer Jill Lepore’s new book that Wonder Woman was created by a man who not only believed in the superiority of the fairer sex but also carried on a polyamorous relationship with two feminists who lived with him in one house, along with their children.

Lepore traces Wonder Woman’s roots back to the turn-of-the-20th-century feminist movement that gave us suffragists and birth-control activism, but it’s William Moulton Marston’s story that carries The Secret History of Wonder Woman. Just like superheroes with hidden identities, Marston never revealed his secret life to the public. Lepore is particularly savvy at pointing out his contradictions: He invented the lie detector test, but he was also a liar who claimed that his girlfriend, Olive Byrne, was a blood relative. He considered women to be mentally stronger than men, but insisted that they’re happiest when they’re submissive. (There’s a reason Wonder Woman always gets tied up: Marston had a thing for bondage.) His comics showed her calling for her mortal sisters to fight off their male oppressors, but in his more scholarly publications, he may have taken credit for research conducted by his wife, Elizabeth ”Betty” Holloway.

Even Marston’s most selfish decisions inadvertently paved the way for women’s rights. After he forced his wife to let his mistress move in with them, Holloway passed off the child rearing to Byrne and forged a career as a lecturer and editor at a time when women were discouraged from working. Following Marston’s death, Holloway, who stayed with Byrne, served as a consultant for the founding issue of Ms. magazine in 1972, with its famous cover line ”Wonder Woman for President.” Yet as young women, they participated in sexual ”training camps” with Marston. Remember that these two women were both major inspirations for a character as wholesome as Wonder Woman, defender of justice and high-waisted, full-coverage underpants. It’s surprising to find that, as Lepore writes, ”theirs was a remarkably kinky New Age.”

The Marston family’s story is ripe for psychoanalysis. And so is The Secret History, since it raises interesting questions about what motivates writers to choose the subjects of their books. Having devoted her last work to Jane Franklin Mecom, Benjamin Franklin’s sister, Lepore clearly has a passion for intelligent, opinionated women whose legacies have been overshadowed by the men they love. In her own small way, she’s helping women get the justice they deserve, not unlike her tiara’d counterpart. But maybe that’s getting too political for a book that’s also a great read. It has nearly everything you might want in a page-turner: tales of S&M, skeletons in the closet, a believe-it-or-not weirdness in its biographical details, and something else that secretly powers even the most ”serious” feminist history — fun. A