Jeff (Jason Segel) is thirty, unemployed, and still living at home with single mother Sharon (Susan Sarandon). In high school, he was a star basketball player, but that was then and this is now. With little drive or motivation outside of smoking pot in the basement, Jeff is inspired by his favorite movie, M. Night Shyamalan's alien invasion thriller "Signs," as he waits for a signal that will hopefully reveal his own fated destiny. Such an omen arrives one lazy weekday morning when a mysterious person calls asking if Kevin is there. Jeff doesn't know a Kevin, but the name will return to him again and again over the next several hours, leading him down a serendipitous path that ultimately will collide with the unusual life-changing events simultaneously occurring to his mother and older brother Pat (Ed Helms).

With 2008's "Baghead," 2010's "Cyrus," and now "Jeff, Who Lives at Home," writer-directors Jay and Mark Duplass have earned the caché to begin working with progressively well-known casts, yet their style and sensibilities have remained fiercely indie-hearted. Mumblecore aesthetics—handheld, frequently zooming cinematography; a loosy-goosy narrative surveying docu-style lifelikeness in lieu of creaky, plot-centric clichés—are all in check, but "Jeff, Who Lives at Home" dares to go a step further as it tweaks the formula of eavesdropping authenticity by highlighting it with moments of unanticipated, transformative grace. Magical realism is tougher to pull off in cinema than in literature, but the Duplass brothers have seemingly mastered this subjective and tonal challenge by allowing it to develop in a natural fashion that doesn't push too hard or spell things out. A deeply felt motion picture of human compassion and complexity—nothing is so easy as to fall the way of archetypes—it also, gradually but succinctly, arrives at a spiritually affirmative denouement, one that has nothing to do with religion and everything to do with the speck of a possibility that greater forces are at work out there. When it comes, the effect is pretty transcendent.

Unable to let go of the mysterious phone call he has received when the average person would just shrug it off as a wrong number and go about their day, Jeff uses it as incentive to leave the house when his mom, from work, asks that he buy some glue to fix a broken window shutter before she arrives home in the evening. It is easy to prematurely label Jeff a burnout slacker, but when he kindly helps an elderly lady onto the bus the viewer must reassess who he is and the goodness inside him. Maybe he should be working and at least be making an attempt to leave his mother's roost, but things aren't always as easy and clear-cut as that, and Jeff is nothing if not an exciting contradiction. Just as Jeff has boarded the city commuter and happened upon a young guy (Evan Ross) wearing a basketball jersey with "Kevin" printed on it—another sign, he adamantly believes—his elder brother Pat has just left for his job at Poplar Paint Company following a nasty argument with wife Linda (Judy Greer). They are having financial trouble as it is, so it comes as a slap in the face when Pat buys a Porsche and doesn't bother telling her about it. Following several more corkscrews that Jeff and Pat aren't prepared for, a chance sighting of Linda with another man propels them in a completely different direction. Is she having an affair, or is he just a colleague? While they put their amateur sleuthing skills to the test, mother Sharon has her own mystery to sort out when a paper airplane with a rose inside lands in her cube, signalling a workplace secret admirer. For someone who has hesitated to begin dating for too many years, she is left anxious and exhilarated at the prospect that someone could be interested in her again.

There are an untold number of joys within "Jeff, Who Lives at Home," but one of its most gratifying is the impossibility to guess where these characters and their lives are going from scene to scene. When the majority of films are strangled by their own customary conventions, here is one that embraces the construct of the mumblecore movement with the feel-good warmth of emotions usually found in a more commercial enterprise. Because it is so unwaveringly arresting, part of the fun is watching the narrative tear away layers as they occur with little foresight into where the story is headed. The eloquently driven, deceptively simple screenplay by Jay and Mark Duplass holds no artifice. It's not their style, for one, and it helps that the actors are given the chance to develop the people they're playing through deeper exploration and improvisation. All of them, in their own way, are you and me, their experiences intimate and ordinary enough to happen to any of us. Thus, Jeff isn't a loser, but a dreamer, hoping the cosmos will help him to find his purpose. Pat looks like he has it all together, but he's arguably more troubled than Jeff, compulsively living beyond his means and allowing his wife to slip through his fingers. As for Sharon, her interoffice investigation holds little danger but high stakes for a woman who had begun to accept romance might not ever be in the cards again.

Jason Segel (2011's "The Muppets") is so genial and disarming on camera and off that it's not hyperbolic to legitimately wonder if he's the most likable actor working today. His face, filled with sincerity and kindness, is a heavenly match for the role of Jeff, an over-aged kid with a too-trusting view of the world that gets him into trouble before luring him one bread crumb at a time toward the exact place he's meant to be. Letting go of all the nebbish traits of his past roles, Ed Helms (2011's "Cedar Rapids") absorbs himself into Pat, his egotism about to receive an overdue reality check. As siblings, Jeff and Pat are very much different people, but the gradual recognition of their imperfections allows them to understand each other in ways they've never stopped to consider. Susan Sarandon (2009's "The Lovely Bones") is simply lovely as Sharon, a character more buttoned-up and vulnerable than she usually gets to play. The respective goings-on at her office—and the little details that lead her, too, toward a fateful moment with her children—run the gamut from amusing to deliciously enigmatic to dramatically gratifying to outright breathtaking. In valuable supporting parts, Judy Greer (2011's "The Descendants") is an exquisite Linda, making decisions she's not proud of but that the viewer understands as she tries to figure out if there is any salvaging her marriage to Pat. As for Rae Dawn Chong (1992's "When the Party's Over"), it's a treat to see her again after flying under the radar for many years. She positively lights up each of her scenes as Sharon's co-worker and confidante Carol.

Set in Baton Rouge, Louisiana—it's so nice when movies branch out from the usual NYC/LA suspects—"Jeff, Who Lives at Home" holds with it a texture and validity that is too rarely captured on film. Its low-key manner, thoughtful nature, and comparative eccentricities may perplex fans who expect this to be a raunchy mainstream comedy like "Forgetting Sarah Marshall" or "I Love You, Man" or "The Hangover," but for audiences tired of the same old thing and willing to take a chance, they'll find something altogether more special. A slice-of-life comedy of a family coming together and a young man's ennui reignited by what he steadfastly believes is fate, "Jeff, Who Lives at Home" is unsuspectingly gentle and sublime.