‘Natural Selection’ Review: One Great Performance Can’t Save Trite-and-True(ish) Comedy

Rachael Harris blossoms when she hits the highway to find her husband’s long lost son in a movie with too many familiar signposts

Why do indie directors love making road movies so much? Is it that diners and motels are a great bargain as locations? Have they overly immersed themselves in the early work of German director Wim Wenders?

Or is it just that the literal forward motion of a car on the highway effectively masks the lack of actual momentum in a screenplay?

That last option comes into play in “Natural Selection,” a mostly contrived comedy whose only real reason for existence is to provide a platform for Rachael Harris to give a true and lovely performance as a middle-age frump who blossoms among the truck stops and the Motel 6es.

Harris is probably best known as Ed Helms’ shrewish fiancée in “The Hangover,” although she also buttered her bread for years as Kirstie Alley’s sidekick on “Fat Actress” and as a one-liner-spewing cultural commentator on VH1’s “I Love the '80s” and its countless sequels. None of her principal claims to fame will prepare you for the understated and occasionally heartbreaking work she does here.

Linda (Harris) lives a godly but stultifying existence in Houston, married to Abe (John Diehl), who refuses to have sex with her because she’s barren, making their coupling non-procreative and thus a sin. When Abe has a stroke at the sperm bank where he’s a regular donor — a pious man still needs an outlet, apparently — the childless Linda becomes obsessed with finding any of her husband’s progeny, so she rifles through their files and comes up with a name and address for Raymond (Matt O’Leary).

Son turns out to be not like father at all; when we meet Raymond, he’s escaping from a Florida jail (he emerges out of a lawn mower cuttings bag like an infant delivering itself via C-section), and the film rather quickly establishes his status as a low-life. When Linda shows up at his door, he finds her Bible-thumping ways irritating, but since he needs to get out of town fast, he happily hops in her car to go visit Abe on his deathbed.

Cue the series of wacky misunderstandings, with Linda bombarding Raymond with decades of unused mothering skills, Raymond getting the sheltered Linda drunk for the first time, and this unlikely couple slowly but surely finding affection in each other’s arms. It’s a highway that audiences have traveled down countless times, but it’s Harris’ skill that makes writer-director Robbie Pickering’s otherwise pedestrian debut feature a trip worth taking.

In other hands, Linda could have been a mean joke, but Harris wears the character’s unflattering eyewear and wardrobe choices with dignity and sweetness. And when Linda’s liberation from her stultifying homelife fans the tiny sparks of her essence, it’s Harris’ refusal to condescend to the character that makes the whole thing work.

When Rachael Harris is off screen, “Natural Selection” resembles one of about a hundred movies that might turn up in the middle of the night on Sundance Channel or IFC. (Assuming that those channels are still showing indie movies and not real ice-fishing housewives or something.) But her performance gives some zing to an itinerary you already know by heart.