On paper, Peter Jackson doesn't seem like an unwise choice to adapt "The Lovely Bones," Alice Sebold's 2002 novel about a young murder victim coming to terms with her untimely death as she watches her family try to cope with their crushing loss. Before doing time (lots and lots and lots of time) in the literary realm of Middle Earth, Jackson explored the supernatural in 1996's all-but-forgotten Michael J. Fox flick "The Frighteners" and peeked inside the often fanciful psyche of teenage girls with his acclaimed breakthrough film, 1994's "Heavenly Creatures." So how is it that a pro like Jackson has utterly bungled "The Lovely Bones," taking a thoughtful, lyrical meditation on grief and turning it into a tacky, mystical thriller?

"I was 14 when I was murdered on December 6, 1973," explains Susie Salmon (Oscar nominee Saoirse Ronan, "Atonement") by way of narration from her own personal heaven. Susie flashes back to happier times to introduce us to her family, which includes dad Jack (a badly miscast Mark Wahlberg) and mom Abigail (an underused Rachel Weisz). It's no spoiler to say that we also meet her neighbor and eventual dismemberer George Harvey, played by a creepily combed-over Stanley Tucci in a Golden Globe-nominated performance. Besides the fact that Susie tells us the details of her death at the outset (the rape is only implied, in a PG-13 way), the unsubtle Tucci telegraphs "Homicidal perv! Right here!" every time he appears on screen.

With Susie serving as our guide, "The Lovely Bones" explores the different ways in which the survivors channel their grief over Susie's unsolved murder. The most wrenching interludes are devoted to Jack's obsession with finding his daughter's killer, a fixation that drives his despondent wife away (but not, as in the novel, into the arms of the cop, played by Michael Imperioli). The film also features Susie's enduringly mutual crush on classmate Ray Singh (Reece Ritchie), though this thread rings hollow thanks to its underdevelopment and casting, Ritchie seeming like a suave collegiate dreamboat compared to Ronan, 13 years old during filming. But despite (or, perhaps, because of) her youth, it's Ronan who holds "The Lovely Bones" together, her expressive sky-blue eyes convincing us of her earthbound pain as well as her excitement over her new (after)life.

And while Jackson employs some evocative set design to illustrate 70's suburbia, he's less successful in his depiction of teen-girl heaven. Yeah, no one knows what a beyond might actually look like, but in this one some stunning land- and seascapes are offset by shifting CGI that is unintentionally ugly in its garishness, bringing to mind the insipid, faux-painterly imagery of "What Dreams May Come." There are a few nail-biting scenes involving George Harvey and the horrible secret he keeps, though Sebold's "The Lovely Bones" wasn't about suspense and vengeance; it was about innocence, loss, and closure. Of course it's cool for an artist like Jackson to put his own spin on source material, but only if it enhances the original vision rather than negating it.