On the face of it, adding putrid, brain-eating zombies to one of the most beloved and intellectually astute comedy of manners in the English language seems like an odd thing to do. On the one side: empire-waisted tea gowns, landed gentry, and a fiercely keen analysis of social strata in the Regency era. On the other: the undead. There have perhaps been odder marriages (the time Quentin Tarantino appeared in an episode of The Golden Girls springs to mind), but not many.

But as any student of Jane Austen knows, her biting social satires are very much about combat, whether it’s Miss Bingley hurling veiled insults at Elizabeth Bennet faster than she can thwack them away or Emma and Mr. Knightley furiously sparring over the former’s spoilt behavior. In 1996, Andrew Davies inserted a scene of Mr. Darcy fencing into his six-part BBC adaptation of Pride and Prejudice, aiming to increase the surly hero’s romantic appeal by demonstrating his prowess with a rapier. In Pride and Prejudice and Zombies, the new adaptation of the 2009 novel by Seth Grahame-Smith, the director Burr Steers goes one further: He makes Darcy one of the most fearsome zombie hunters in all England, amid a “virulent and gruesome plague” that’s wreaking havoc in the country. And Elizabeth isn’t just his sparring partner in a metaphorical sense—she’s an equally deadly warrior who can match him both intellectually and physically, at least when it comes to decapitating the undead.

One of the great surprises of Grahame-Smith’s novel was that it was literally Pride and Prejudice, as written by Austen, with a few lines about zombie warfare spliced into the text. And it worked! In the book’s zombie subplot, Elizabeth and her sisters have been trained in the martial arts in Shaolin, China, making them one of Hertfordshire’s most vital lines of defense against the increasing zombie incursion. But the movie, sensing that a genteel romantic satire with less than five percent brain eating might be tonally awkward, rejiggers things to allow for more cinematic potential. In an early sequence, the camera lingers on the Bennet sisters’ undergarments as they arm themselves beneath their muslin frocks. Meanwhile, Darcy (Sam Riley) travels around England’s stately homes looking for aristocrats who’ve fallen victim to the plague and finds a young blonde cheerfully gnawing at the throat of an elderly man’s corpse.

Steers leans all the way in to the cognitive dissonance of his source material, amping up the blood, brains, and horror while retaining the key romantic plot points of the novel. Elizabeth (Downton Abbey’s Lily James) is a spirited and independent young woman whose pride is mortified when she overhears Darcy criticize her “tolerable” appearance at a ball; Jane (Bella Heathcote) is her beautiful and sweet-natured older sister who falls in love with Mr. Bingley (Douglas Booth), a wealthy and eligible gentleman who takes a house nearby.

The conflicts Austen sets up so well are mostly pared down in favor of the bloodier scenes mandated by the soulless corpse element. Miss Bingley (Emma Greenwell) is reduced to a minimal irritation, Mrs. Bennet (Sally Phillips) embarrasses her eldest daughters only fleetingly, and Lady Catherine de Bourgh (Lena Headey) becomes a fearsome warrior herself who sports an eyepatch thanks to a battle injury and is less an obnoxious, pompous aristocrat than a strong female role model. Mr. Collins (Matt Smith) is the lone character whose presence is fortified, but even he gets a reasonably sympathetic interpretation thanks to Smith’s simpering, winking charm.

Mr. Wickham (Jack Huston) remains the primary antagonist, although his motivations are somewhat altered—he becomes convinced that zombies can be deterred from eating human brains, and seeks to encourage a detente between the two rival forces. As for the zombies themselves, they’re visually horrific (with their skin peeling off and their bonnets covered in blood) but Steers seems unable to find a balance between the comedy of the source material and the eeriness he clearly wants to channel. The movie isn’t quite satire, but nor is it serious; as it barrels toward a high-stakes climax in which London has fallen and the zombies are fast approaching, it veers all the way into action territory and seems to forget it was ever ironic. Less Austen, more Armageddon.

Still, Pride and Prejudice and Zombies has its assets, namely James’s unabashed charisma and Charles Dance’s all-too-brief moments as the hard-done-by Mr. Bennet. (Riley is oddly awkward and maladjusted even for Mr. Darcy—the character seems to hint that he’d be more at home at a Marilyn Manson concert than felling the undead at Pemberley—and Booth’s Bingley looks like a Burberry model, which isn’t surprising, given that he is one.) Movies have proven that zombies can be funny (Zombieland, Shaun of the Dead), and that adaptations of classic novels can be thrilling. But all three at the same time? That’s an awful lot to bite off in one go.