For anyone unfamiliar with the origin of the Wonder Woman comic books, it may come as a shock to learn that the superhero’s 1941 genesis involves sadomasochism, bondage, kinky role-playing, and a scandalous ménage á trois. You’d think, based on such a juicy history, that a movie made about the Amazonian princess’ creation would be tantalizing, if not downright titillating. But you’d be wrong: In the hands of writer/director Angela Robinson, this somewhat salacious true story turns out to be snooze-inducing rather than sexy.

Wonder Woman was created by former Radcliffe professor William Moulton Marston (Luke Evans), a proponent of DISC theory that emphasized dominance, inducement, subjugation, and compliance as the four pillars of human behavior. As presented in the film, Marston is most interested in inducement, in which a person persuades a subject to do what they want. And what Marston wants is to study—or rather, seduce—Olive Byrne (Bella Heathcote), a beautiful 22-year-old student in his psychology class who is also the niece of feminist icon Margaret Sanger. However, Byrne is more attracted to Marston’s brilliant, forward-thinking wife Elizabeth (Rebecca Hall). Byrne soon moves in with the Marstons and the three embark on an alternative, free-love lifestyle, which gets Marston fired and eventually yields four children, two by Elizabeth and two by Olive. Years pass, and then one day Marston sees Olive dressed up in a tight, bare-shouldered costume, thigh-high boots, twin silver bracelets, and a tiara, while holding a strand of thick rope like a lasso in a bit of bondage playacting; he seizes upon this as the inspiration for a female superhero. He takes his proposal to comic-book pioneer M.C. Gaines (Oliver Platt), and a new champion of justice is born.

The movie is told via flashbacks as Marston is grilled by Josette Frank (Connie Britton), the sanctimonious director of the Child Study Association of America, as she decries Marston’s depiction of violence, bondage, spanking, torture, and implied homosexuality in the Wonder Woman comics (Marston based his story lines on his fantasy-filled home life). It’s an odd device that detracts from the overall story, although Britton is quite good as the high-minded inquisitor. As for the rest of the cast, Evans is dull and unconvincing, as is Heathcote, but Hall is simply dynamic in a performance that is equally ferocious and fragile.

Robinson tries hard to paint Marston as a progressive freethinker and champion of women’s rights, but Elizabeth nails it when she tells him to stop justifying the whims of his own sexual desire with science after he refers to a bondage scenario as a research experiment. It’s a blistering rebuttal that gets to the heart of her husband’s erotic ambitions, and one wishes that Robinson had dealt with the rest of Marston’s story this honestly. Instead, she tries to scrub it clean and presents the threesome’s lives as nothing more than domestic bliss. This approach would seem small-minded in a story about a conventional marriage, let alone one involving polyamory. Robinson wants her film to be both titillating and traditional, and it ends up in a muddled middle ground. It commits the worst cinematic sin: It’s boring.