You’ll either be inspired or nauseated by "The Odd Life of Timothy Green." This is a member of the nauseated camp speaking.

The movie from novelist and filmmaker Peter Hedges, author of "What’s Eating Gilbert Grape" and creator of Katie Holmes’ lovely independent feature "Pieces of April," strains to Disney-ize the family dysfunction territory he explored so well in those works.

In "Timothy Green" it’s all gone flat, mushy and hollow. Adapting a short story by Ahmet Zappa (son of Frank), writer-director Hedges tries for old-fashioned wholesomeness only to flounder amid a well-intended but sappy tale of a childless couple mystically granted a test run at parenthood.

‘THE ODD LIFE OF TIMOTHY GREEN’ Rated: PG Opens today

Hedges assembled an impressive cast, led by Jennifer Garner and Joel Edgerton as the parents, and the actors buy into the story’s conceits wholeheartedly. The characters are simplistic and artificial, though, behaving in ways that often are insultingly naive and sometimes just plain stupid.

A movie’s in trouble when the characters are just as unbelievable as the premise.

That very odd premise of "The Odd Life of Timothy Green" is this: Cindy and Jim Green (Garner and Edgerton) desperately want a child, and of course, they can’t have kids.

On a whim that wafts in from nowhere, they write down the perfect qualities that their perfect child would have in a perfect world where they could procreate. Musically, the kid would rock out. Their kid would be funny, not cruel funny but, you know, a laugh riot. This kid would not be athletic, but would have one glorious chance to win the big game.

Cindy and Jim put these offspring wishes in a box and bury it in their garden. And after a dark and stormy night, during which it rains nowhere else in their little town except the Green homestead, a boy named Timothy (CJ Adams, who had a small part in Hedges’ "Dan in Real Life") emerges from the ground, wanders into the house and starts calling them Mom and Dad.

The Greens accept him as their own without question, just as they accept that he mysteriously has green leaves growing out of his ankles.

Then Timothy proceeds to sow little graces and nuggets of wisdom to his overprotective, ill-prepared parents, along with everyone else in town: Cindy’s judgmental sister (Rosemarie DeWitt), spiteful boss (Dianne Wiest) and doting aunt and uncle (Lois Smith and M. Emmet Walsh), and Jim’s high-handed dad (David Morse) and weasel of a boss (Ron Livingston) at the local pencil factory.

Rapper Common plays Timothy’s callous soccer coach, and he’s like almost everyone else in town: mean, and sorely in need of the lessons in decency, hope and compassion that Timothy spreads like some strange little organically grown sage.

OK, it’s a fairy tale for adults. We can make allowances for reality. We get it.

But even in the most far-out of make-believes, storytellers have to make an audience want to believe, and "Timothy Green" never does that.

Fantastic though the story may be, the people in it need to make it feel real, and no one in "Timothy Green" has any claim to authenticity. The closest Hedges comes is in the relationship between Timothy and an older girl at school (Odeya Rush), an outsider who forms a sweet first-love bond with the boy. Even that’s treacly, though it goes down easier than the excess of sentiment in the rest of the movie.

"Timothy Green" is a very pretty movie to look at, awash in postcard images of rural America and lush colors that turn from verdant to autumnal as the story unfolds.

Beneath the pretty pictures is a silly, shallow stab at Capra-corn, the sort of magical story of simple, genuine people mastered by Frank Capra with such films as "Meet John Doe" and "It’s a Wonderful Life."

Sadly, "The Odd Life of Timothy Green" is all corn, no Capra.