When childless couple Cindy (Garner, after Sandra Bullock passed) and Jim (Edgerton) finally get confirmation they can't have kids they dig out a bottle of wine and compile a list of the attributes of their phantom child.
Burying the list in a box in the vegetable patch, no-one is more surprised when - Day of the Dead-like - a small child emerges from the earth during a thunderstorm and scampers into their house.
After a quick bath and a few half-hearted inquiries, they put the arrival of the youngster - christened Timothy - down to fate and agree to raise him as their own, even if he has got leaves sprouting out of his ankles.
First they've got to overcome the suspicions of the local community - a tiny pencil-manufacturing town on its uppers - as well as their respective families: Jim's disapproving dad and Cindy's social-climbing sister.
While Jim and Cindy flail around, making bad parental choices but never, ever showing less than unconditional love, Timothy displays an unerring instinct for tact, kindness and diplomacy, dispensing a national curriculum of life lessons.
In an era when live-action children's films are largely losing out to the CG spectacle of Pixar and its rivals, this unabashed celebration of family stands out as a welcome oddity.
It's not afraid to deal with darker issues - that childhood isn't forever - and Adams plays it just the right side of mawkish while Hedges makes sure it's anything but a smooth ride.
Timothy Green teaches us that life isn't black and white.