Pride and Prejudice and Zombies Lily James, Sam Riley, Lena Headey. Directed by Burr Steers. Rated PG-13. Opens Friday citywide.

Based on Seth Grahame-Smith’s mashup novel, Pride and Prejudice and Zombies is, unsurprisingly, a fairly poor zombie film, but, surprisingly, a pretty good Jane Austen film. Director Burr Steers once made the literate coming-of-age film Igby Goes Down (2002), about smart, well-read people, and he enters Austen’s world, telling the tale of Elizabeth Bennet (Lily James) and Mr. Darcy (Sam Riley) with springy enthusiasm, confident ease and even humor. The old familiar characters—last seen on the big screen in Joe Wright’s 2005 adaptation of Austen’s 1813 novel—generate genuine chemistry and love pangs, while leather boots creak and bosoms heave. Matt Smith (of Doctor Who) absolutely kills in his hilarious scenes as the ineffectual pest Mr. Collins (now Parson Collins).

But the zombie stuff and martial arts fighting feels tacked on, as if by committee. It’s too bad that Steers couldn’t have hired a co-director who actually cared about undead lore. These are ill-chosen fast zombies, better suited for exercising than for nightmares; the gore is deliberately avoided to secure a box office-friendly PG-13 rating, and what gore is shown is stuck on with smeary, third-rate computer effects. The choreographed fighting is lazily shot, stopping every now and then for a cursory chest-kick or head-butt. For a while, the enjoyable human aspect of the plot is enough to keep the movie pulsing, but as the third act comes around, it begins lumbering through more and more frequent dead spots. Even the ending is an indecisive split, attempting to please both sets of fans and dissatisfying all.