First-time feature director Robbie Pickering shows promise to spare in Natural Selection, a small gem of an indie movie whose rewards far exceed its bare-bones budget. The marvelous Rachael Harris stars as Linda White, a real-life Texas housewife, minus the makeup, teased hair and spike heels. For 20 years, Linda has been a good Christian wife to Abe (the excellent John Diehl), a hypocrite who hasn’t had sex with her since she was diagnosed as infertile—don’t you know it’s a sin to spill your seed when impregnation is impossible? Imagine Linda’s shock when not-so-honest Abe has a stroke while jerking off at a Houston sperm bank he’s been sneaking off to. With death knocking on Abe’s door, good wife Linda decides to track down one of the results of Abe’s mammoth wanking sessions. He’s Raymond (Matt O’Leary), an escaped con Linda finds in Tampa, Florida, where he avidly avoids the cops and soap and water. The road trip, with Linda driving Raymond back to Texas to visit daddy Abe, is the heart of the movie. Credit Pickering’s deft script for avoiding the usual clichéd speed bumps, though sex and lies are on the menu. No fair giving away the film’s secrets, which involve Linda’s bitchy sister Sheila (Gayland Williams) and Peter (Jon Gries), Sheila’s minister husband with a long-standing crush on Linda. What matters is the magical alchemy between Linda and Raymond. Or should I say the connection between Harris and O’Leary, two actors ready for every curve ball the script throws them. The scene in which they break into a diner and talk their hearts out is outstanding and a calling card to mark Pickering’s potential as a filmmaker. O’Leary is ultra-fine as a shut-off dude gradually opening up to feeling. But even Darwin would cede Natural Selection to Harris. Best known as Ed Helms’ nagging fiancée in The Hangover, Harris is just perfect without ever looking down on Linda’s faith in God and herself. Her performance earns a special kind of glory.