The latest incarnation of Jane Austen’s Elizabeth Bennet is a most accomplished young woman. She’s studious, spunky, quick-witted and multilingual. And you should see the way she slaughters zombies. After all, she studied combat in China and can read “The Art of War” in the original Mandarin.

For all the blood and guts, “Pride and Prejudice and Zombies” is surprisingly faithful to Austen’s beloved 1813 novel (minus the combat). But the genre mashup never quite meshes.

For the uninitiated, here’s a brief rundown of the movie’s slow journey to the big screen. In 2009, novelist Seth Grahame-Smith (of “Abraham Lincoln: Vampire Hunter” fame) wrote the bestselling takeoff on “Pride and Prejudice,” and the movie rights were immediately snapped up. Since then, various directors and stars have been attached to the project. Just imagine what Natalie Portman could have done with the lead role under the direction of David O. Russell.

Instead, director and screenwriter Burr Steers (“Igby Goes Down,” “17 Again”) has been tasked with taming the wild beast. He, at least, has a winner in Lily James, the “Downton Abbey” alum who starred recently in “Cinderella” and the BBC miniseries “War & Peace.” She makes a lively, lovable Elizabeth, playing it straight as a woman who proclaims, early on, “I shall never relinquish my sword for a ring.”

The Bennet girls are well-versed in fighting, which is necessary because England is overrun with zombies. And the civil war between humans and the undead is only getting worse. When we first see Mr. and Mrs. Bennet’s five daughters, they aren’t sewing or drawing; they’re cleaning their guns and polishing their knives. Preparations for the Netherfield Ball include the requisite corset tightening and cheek pinching but also stashing daggers in holsters next to the girls’ garters.

This is all gently amusing. But everyone knows “Pride and Prejudice” isn’t about action or laughter; it’s about romance in a stratified society. Enter the rich, prickly Mr. Darcy (Sam Riley). Here, he wears a long leather coat and delivers his lines with a husky smoker’s rasp, but he’s also a first-class zombie hunter - so his haughtiness is earned. During his first meeting with Lizzie, Darcy offends her with insensitive comments, as in the book. But he also enrages her by blowing the head off a perfectly civil zombie that Lizzie has been conversing with.

“I narrowly saved her life,” Darcy remarks with satisfaction.

That line aside, plenty of dialogue has been taken straight from Austen’s original. Ingeniously, the sisters still have their heart-to-heart talks, but now they chat while training for hand-to-hand combat. And Darcy and Lizzie share that charged moment when he proposes and she rebuffs him. This time, however, they do it while punching, kicking and wrestling each other.

Yet for all the original elements that remain, something is amiss. For one thing, Darcy fails to transition from a jerk into a worthy suitor. So much for romance. And the middling CGI makes the zombies look like a crowd headed to a Halloween party.

There are some laughs along the way, most of which come courtesy of Matt Smith, playing Lizzie’s cousin and suitor, Mr. Collins. That character’s clueless self-importance supplies the most comical moments in the original story, and Smith’s solid delivery and goofy facial expressions make his idiocy even more riotous.

“Pride and Prejudice and Zombies” delivers what its title promises: a little romance and some undead villains, plus a bit of comedy. But this overly busy riff on Austen’s winning formula doesn’t justify all the tinkering.