Not for Teacher: Everyone falls for the princess of Montpensier, including her much-older instructor.

Horses and scenery and battles and costumes: That’s basically the essence of the French-language The Princess of Montpensier, an intended 16th-century bodice-ripper that writer-director Bertrand Tavernier adapted from a short story and turned into a 139-minute snoozer. Set in 1567 during the civil war between French Catholics and Protestant reformers, the film buries its romance in confused politics and its women in petticoats, all but snuffing out the passions that allegedly drive the story. The result is a turgid bore that can’t be saved by ornate outfits or its lead’s pretty pout.

The film begins with a gruesome battle, one in which our grown-up hero, Count Chabannes (Lambert Wilson), kills among others a pregnant woman. Disgusted with himself and the war in general, he deserts, but in the process reconnects with a former student, the prince of Montpensier (Grégoire Leprince-Ringuet). Back at the castle, a father (Philippe Magnan) is negotiating a wedding between his already-betrothed daughter, Marie (Mélanie Thierry), and the prince. Marie loves neither the prince nor her intended, however; her heart belongs to her fiancé’s rakish brother, Henri de Guise (Gaspard Ulliel). Mon dieu!

Little matter. Forced by her father to “submit,” Marie marries the prince and even convinces herself she’s happy and over Henri. (Which, for all the film’s running time, appears to happen overnight.) When the prince is called off to war, he leaves Marie in his teacher’s hands, asking Chabannes to school Marie in the arts. Alas, Chabannes falls in love with Marie, too, a crush that’s mentioned exactly twice at what are essentially the film’s bookends. Then Henri starts bumping into her again, and wouldn’t you guess that Marie hasn’t really quashed her feelings for him after all? Also lusting after her is the king’s brother, the Duke of Anjou (Raphaël Personnaz), a dandy who is unrepentant in his flirtations with the prince’s wife.

Interrupting all the sexual tension are more battle scenes—and if you’re not familiar with the history of the period, Tavernier doesn’t do much to clue you in, making all the fighting a meaningless muddle that distracts from the plot’s three- (five?-)way love story. Also burying the plot is the death of Marie’s mother (an incident not shown, but mentioned after the fact) and her father’s subsequent marriage to her childhood friend. Because a legion of plotlines isn’t nearly enough, Tavernier overdecorates his dialogue, leaving many narrative question marks in the wake of the characters’ dizzying exchanges.

The film’s final nail is the princess herself. Thierry is inarguably fair and gorgeous. But she’s also cool, and you never quite believe in Marie’s fire for Henri or her unhappiness with the prince; this isn’t a girl you can imagine ripping her bodice for anyone. (Though one of the film’s most vivid scenes involves her wedding night, as a sizable audience watches a naked Marie get scrubbed down for consummation and waits for her moans and the prized bloodied sheet.) Tavenier’s portrait of 16th-century life is ultimately a paradox: One that’s spot-on in big-picture details but a mess when you get up close, at once overstuffed and not nearly meaty enough.