StarSolidStarHalfStarOutlineStarOutline(1.5 stars)

In 2004, writer-director Kevin Willmott made “C.S.A.: Confederate States of America,” a queasily prescient satire in which the South had won the Civil War.

There are moments in “Antebellum” that recall Willmott’s audacious revisionist history, but they're fleeting, and by the time this muddled misfire of a fantasy-horror film reaches its outlandish climax, any and all comparisons can only be invidious. It can now be stipulated that anything featuring Janelle Monáe will be eminently watchable: She exerts centrifugal force on the camera, and the audience, drawing us to her with a combination of delicacy and sheer power of personality. But even Monáe’s magnetism can't elevate “Antebellum” above roots that are firmly planted in the blood and soil of pulp exploitation, shaky liberal earnestness and rank opportunism.

“Antebellum” opens with a masterfully executed single shot that pans across a Civil War-era plantation, where a tableau of rebel soldiers gives way to a beatific scene of domesticity and, finally, to a group of enslaved field workers picking cotton. It has the manicured, too-perfect quality of a dream, or a stage set, which might be chalked up to aesthetics until the viewer realizes that other things are in play. Eden, the enslaved laborer played by Monáe, is determined to escape, despite the fact that her most recent attempt has been met with failure. Her captivity is made all the more perilous by the fact that she's repeatedly raped by a Confederate officer known only as Him (Eric Lange).

In many ways, “Antebellum” hews to the classic narrative arc of someone desperately trying to get home. But in this instance, just where Eden belongs becomes the movie’s core mystery. Written and directed by first-time filmmakers Gerard Bush and Christopher Renz, this is a film whose kaleidoscopic sense of time and place produces shocking doglegs meant to lead the audience into a meditation on America's legacy of racism. As “Antebellum” points out, that unresolved history — of humiliation, erasure and violence perpetrated on Black bodies — entailed its own form of resistance, here embodied by Gabourey Sidibe in an unapologetically liberated performance as the kind of “sassy” best friend that's right at home in a modern-day rom-com.

Of course, the sassy best friend has become its own kind of offensive trope. So what might have been an exhilarating grace note winds up feeling forced and patronizing in “Antebellum,” which is clearly fueled by righteous outrage, but never quite sticks its own tricky landings. (It doesn't help that the dialogue and characterizations, especially of a grotesquely conniving White woman played by Jena Malone, are overbroad and bluntly obvious.) When the film’s true context becomes clear, it feels like a smart idea that's been smothered in sensationalism and the spectacle of Black suffering; what should be a triumphant final image instead looks smug, simplistic and unearned. For a minute there, “Antebellum” looks like it might deliver a timely reckoning with the most pernicious undersides of the American myth. Instead, it offers viewers an intriguing idea that’s simultaneously undercooked and awkwardly overstated.

R. Available via various premium on-demand platforms. Contains disturbing violent content, strong language and sexual references. 105 minutes.