‘Life After Beth’ shallow but gravely funny

You’ve gotta figure “Life After Beth” started as a title. Somebody said “life after death,” a punster changed it to “Beth,” everybody was ROFL, and the deal got done.

Well, worse movies have been started with better intentions. Until writer-director Jeff Baena loses his way in the last third, he provides a fresh, silly-touching take on the zombie genre. Even the title turns out to be a joke, because Beth’s in virtually the whole film. (Aubrey Plaza, who plays her, gets top billing.)

After Beth gets a snakebite on a solo hike and dies, Zach (Dane DeHaan) goes to her funeral and regrets all the things he never told his girlfriend while she was alive. Not to worry: She shows up at her parents’ house a few days later, smelling of graveyard earth through which she has clawed, with no memory of her absence.

Her parents (John C. Reilly and Molly Shannon) speak of a Bible-style resurrection. Zach hesitantly uses the z-word. But all three welcome her back, and Zach declares his renewed love. If patches of Beth’s skin didn’t keep peeling off, all could be well.

Alas, she begins to rage inexplicably, acquire unusual strength and start to look at people as if they might be tasty. Can love, as Zach insists early on, really conquer all?

If you wanted to, you could see this movie as an allegory about people who love each other but can never connect. Or maybe it’s a warning to parents who turn a blind eye to children’s failings until the family self-destructs.

But just as you’re sorting this out, the story starts to fray. We turn down the old Apocalypse Road, with more and more zombies turning up inexplicably. Suddenly they’re at war with the residents of the unnamed seaside city, and Baena has no idea where to take the screenplay.

He has one prior screenwriting credit – “I Heart Huckabees,” written with David O. Russell – and some of that quirky sense of humor enlivens “Beth.” The zombies can be calmed only by playing them smooth jazz in the Kenny G mold, and Beth’s main post-burial drive is for all the sex she denied herself in life.

Yet the cast can’t grapple with Baena’s late-inning mood swings, and the use of familiar actors in tiny roles proves a distraction: Paul Reiser, Cheryl Hines, Anna Kendrick, Alia Shawkat and Garry Marshall pop in and out and have little to do.

UNC School of the Arts grad DeHaan holds the movie together for quite a while. He tends to play villains (“The Amazing Spider-Man,” “Kill Your Darlings”) or angsty types (James Dean in the upcoming “Life”), so it’s good to see him in an obvious comedy. Even here, he gives a deeply felt performance: He’s the only 27-year-old actor I know who wears a haunted look naturally.