The title of Little Sister is built around a double entendre, in that it refers to lead character Colleen’s status as both the youngest member of a particular family unit and as a young nun in training. That layer to the title makes itself evident within the opening 10 minutes or so of Zach Clark’s follow-up to White Reindeer (2013), but anyone expecting something especially cutesy from that particular quirk can be rest assured that Little Sister does not fall into the trap of overly precious Sundance bait, even with a narrative template that’s somewhat reminiscent of a certain film from another Zach, Garden State. The fact that Little Sister actually had its world premiere at SXSW also nullifies that, but that’s beside the point.

No, this is a much spikier, scuzzier offering than it may initially seem from a scan of a plot synopsis. It’s neither as cloyingly sentimental as a Zach Braff film, nor too far in the opposite direction to the realm of smug toxicity, like an opening quote from one Marilyn Manson briefly suggests it could be.

So about that plot, then. Here we have a young person, the aforementioned Colleen Lunsford (Addison Timlin), estranged from her family due to career pursuits and considerable distance from her childhood home in Asheville, North Carolina. She’s a novitiate, yet to take her vows for full-blown nunhood, in a convent in New York City in 2008, as the backdrop of Barack Obama’s first presidential campaign is at fever pitch. Like the rest of America, the fallout of the post 9/11 world has loomed large over the Lunsfords, and it’s the consequences of one tragic aspect of the Bush administration that draws Colleen back to Asheville for a few days.

Her older brother, Jacob (Keith Poulson), has recently returned home from Iraq with his face horribly burned, locking himself in the family’s pool house, refusing visitors. Email pleas from mother Joani (Ally Sheedy) coax Colleen back, so as to try coaxing of her own to lure Jacob back into society. Not entirely sure the girl has fully dismantled herself from the outside world, the mother superior (played by 80s genre favourite Barbara Crampton) says, “It took God six days to create the universe. You should be able to get your act together in five.”

Colleen’s arrival back home quickly spurs some red flags as to why she might have fled in the first place. Mother Joani and father Bill (Peter Hedges) are burnouts of Generation X whose response to the Bush years has been a mix of booze, weed and pills, some of the latter prescribed in Joani’s case due to manic-depression and recovery from a suicide attempt. Physical and emotional recovery’s the big thing in the household, with Bill also recovering from a failed acting career and Jacob’s fiancé, Tricia (Kristin Slaysman), trying to resurrect passion from her battle-scarred lover who just wants to be left alone. With fog swirling around the outside of the home in Daryl Pittman’s autumnal cinematography that’s cloaked in a dreamy haze, it’s almost as though the structure is a prison for lost souls somewhat out of time — some longing for better days, some whose future has been disrupted, and one who’s venturing back to make some sense of the past’s role in her moving forward.

Colleen’s newfound piety drives Joani up the wall, but the little sister eventually cracks the Jacob nut by shedding at least some of her devout veneer and re-embracing the darker exterior of her teen years as a means of reconnecting with her brother. Back come the dyed hair, dark make-up and fondness for Gwar for this former goth/metalhead, though the wild child aesthetic only extends to her outer appearance. There’s still plenty of opportunities for the virginal Colleen to be tempted by the vices of alcohol and drugs, some of which are inserted into her system unwillingly by members of her messy family.

As much as writer-director Clark deals with reconciliation and recovery, he also never shies away from the cruelties and insecurities that exist in the interplay between family members, even when they’re ostensibly getting along. One such memorable exchange sees Joani say to Colleen, “When you were growing up, Dad and I thought you’d become a lesbian Satanist.” Colleen’s reply is, “Sometimes I think you’re sad I’m not.” It’s a razor-sharp face-off that speaks to the success of Clark and his cast’s realisation of this family unit. They are not just props for dysfunctional family kookiness. There is palpable empathy on display for everyone; an intimate and humane quality to every interaction even when the film’s sense of humour veers towards the wry, though that comedic register helps in making the dramatic pain all the more cutting. Clark’s tonal balancing act is achieved with a degree of grace worthy of his central heroine’s spiritual aspirations.

And what a central heroine he has. Little Sister has a uniformly strong cast, but Addison Timlin gives one of those star-making turns that, if the universe is at all just, will be but the first prominent stepping stone for an extraordinary career. I would compare it to the level of Elizabeth Olsen in Martha Marcy May Marlene, and not just because there’s a vague physical similarity between the two actors. Few young actors could imbue the high-concept part of an ex-goth nun with the level of subtlety that Timlin does, nor successfully navigate all the demanding contradictions of Colleen’s characterisation with such a consistent degree of both sharpness and the requisite grace the role requires.