I'm not sure if it's worse to see A Quiet Little Marriage if you haven't decided whether or not you want to have kids, or if you have. But as a provocative portrait of marital disharmony, Mo Perkins takes the idea of dissenting opinions about child-rearing to its ultimate, dramatic end in his feature directorial debut. Mary Elizabeth Ellis, probably best known as Charlie's crush object 'the waitress' on It's Always Sunny in Philadelphia, plays a hopeful mother whose bid for a baby is scuttled when her husband's troubled family history prompts him to deny her plea for them to start a family.

Olive (Ellis) and Dax (Cy Carter) are happily married, but not without problems: her father Bruce (Michael O'Neill) suffers from Alzheimer's, and his brother Jackson (Jimmi Simpson) is at least a borderline alcoholic who comes around only when he needs money. After Bruce accidentally slugs a nurse during one of his bouts of senility, Olive begins to contemplate her future with Dax, and proposes they have a baby. Dax refuses categorically, so she decides to take the decision out of his hands by sabotaging her diaphragm. But when he discovers her plan, Dax decides to put birth control pills into her morning coffee; eventually, the mutual deception causes their relationship to deteriorate, culminating in a fight that not only jeopardizes the prospect of children, but the future of their marriage.

Perkins and his two stars came up with the story, and while they certainly explore all of the avenues opened by the idea of dueling partners deciding the fate of future children, the film feels occasionally too conventional, and moves too slowly to offer any real surprises. (I was watching the film at home and joked about a few directions the story would go, and was mildly disappointed to find I was right in most cases.) That said, the performances are all pretty good – low-key, subtle and effective – and the plot's twists and turns are handled with dexterity and nuance. Ellis and Carter play a convincing couple, both when their marriage is strong and when it's faltering, but a supporting cast that includes Melanie Lynskey and Charlie Day (Ellis' real-life husband) fleshes out the landscape of different sorts of relationships – considerate, oblivious, affectionate, complacent – and gives the film a realism and authentic context for their central conflict.

Because of its high-profile wins at festivals like Austin and Slamdance and the wealth of familiar faces in the cast, Perkins' debut seems destined to break out to larger audiences, and it certainly shows enough promise to deserve the wider attention. But it could also benefit from some editorial tightening, as is often the case with smaller films that are freer and less focused than conventional crowd-pleasers, particularly in its time-lapse interstitials, which convey too much time when a mounting sense of urgency or at least intensity is what would strengthen the story. Overall, however, A Quiet Little Marriage is a quiet little triumph, a tale that maximizes the potential of its character-driven conceit, and most effectively, a movie to see if you want to start a debate, but definitely not to resolve one.