Zach (Dane DeHaan) mourns after the sudden death of his girlfriend, Beth (Aubrey Plaza), but she returns as a zombie in “Life After Beth.” (Greg Smith/Sundance Institute)

With its accomplished cast and darkish, off-kilter worldview, “Life After Beth” at first seems to be an unconventional rom-com with a sly, skeptical streak. But the promise of its premise is squandered all too soon in what becomes yet another tiresome exercise in the way-overworked zombie genre.

Written and directed by Jeff Baena — who co-wrote David O. Russell’s witty, existential detective movie “I Heart Huckabees” — “Life After Beth” is an aimless, slight and ultimately off-putting example of a clever title in search of a movie. The search, in this case, never comes to fruition in anything other than cliches and facile, clunky plotting.

Dane DeHaan plays Zach Orfman, who, when “Life After Beth” opens, is trying to buy black napkins for a memorial lunch for his late girlfriend, Beth (Aubrey Plaza), who died suddenly during a hike in the Southern California hills.

Stunned and grief-stricken, Zach strikes up a friendship with Beth’s parents (John C. Reilly and Molly Shannon), who are keeping up a brave front even as they sort through Beth’s things. But within days of Beth’s passing, they suddenly turn away from Zach, for reasons that become clear after he catches a glimpse of his dead girlfriend through their living room window.

One of the arguments that Zach has with Beth’s Jewish family in “Life After Beth” is whether their little girl has been resurrected (“like Jesus,” according to her folks) or has turned into a zombie. Rather than stay in that provocatively ambiguous space, Baena goes straight into genre territory, complete with rotting flesh, guttural growls and scary, superhuman strength. DeHaan and Plaza bring focus and sincerity to their roles, and both are convincing as college-bound teenagers in love. When Anna Kendrick shows up in a giggly cameo, she ignites the screen with totes adorbs fizz.

But that’s about as good as it gets. “Life After Beth” mostly trafficks in hackneyed vignettes of suburban life — Zach’s parents (Paul Reiser and Cheryl Hines) are blandly clueless and constantly eating dinner — and, in its final third, gruesome visual effects that feel warmed over from the far superior 2009 film “Zombieland.” Even one of the film’s more novel comic touches, involving smooth jazz and Kenny G., quickly wears out its welcome.

The film’s payoff, a sight gag with odiously misogynistic symbolic undertones, harks back to “can’t live with ’em, can’t shoot ’em” humor that was dated a decade or two ago. “Life After Beth” may have revived the ultimate girlfriend from hell, but it’s still wan, listless and derivative in bringing her to undead life.

R. At West End Cinema. Contains pervasive obscenity, some horror violence, sexual content, nudity and brief drug use. 88 minutes.