The smallest details make the strongest impact in Family Symmetry, Adam Samtur's occasionally involving but ultimately uneven new Midtown International Theatre Festival play about Obsessive-compulsive disorder. The man suffering from it, Allen Heywood (Leo Goodman), is obsessed with properly opening and securing the locks on his front door, precisely measuring his shoelaces, tugging his shirt just so during the buttoning process, and don't even think of rearranging those photographs on the table in the hall.

Samtur, who also directed, ensures that Allen is forever consumed with his pursuit of an impossible order, the right launching pad for a play about how some chaos, particularly in a marriage, can actually be a good thing. And there's a considerable history of that here. Allen's institutionalization following a serious OCD outbreak three years earlier was the impetus for him to marry his college girlfriend, Suzanne (Olivia Gilliatt), who gave up a potentially stellar career as a doctor to instead care for Allen and has never exactly forgiven him for requiring that sacrifice of her.

In the first half of the play, Samtur shrewdly establishes the couple's codependency and the desires between the two that alternately interlock and conflict. The extent of the magnetism that originally attracted them is very clear, as are the differences in outlooks and personality that seem destined to wedge them apart. (Whenever Suzanne is alone, for example, she's addicted to jazz music, which with its reliance on improvisation Allen would obviously never allow - a wonderful tiny touch.) If much of the dialogue feels a bit soft and pat around the edges, it has a depth and darkness in the earliest scenes that signal this play a more effective rendition of a difficult psychological problem than the cursory glances given bipolar disorder by the Broadway musical Next to Normal.

But as the action presses on, Samtur reveals - or rather changes - too much about Allen to allow him to maintain our sympathy, to say nothing of equal footing in his struggle against Suzanne's mounting indifference. If you don't get the distinct impression of the playwright taking sides in their argument, it does seem that Samtur believes the story needs to be prodded because it won't tell itself, and that's when the play loses its believable luster. One act of unforgivable violence that comes to light in the final scene is too shocking to even stun - it feels more like a playwright's mean-spiritedness than the settling of the final rubble pile of a relationship long in the collapsing.

Until then, Goodman gives Allen an appropriately warm and cluttered personality, making him every bit the man who's watching his life spiral out of control; his tense muscle movements and barely perceptible flinching when things are secretly rearranged are dazzling tiny tricks. Gilliatt brings a weary sophistication to Suzanne that convinces in all but the angriest, loudest scenes - then she simply pushes too hard, losing the compassionate underpinnings to the character that so fuel the earliest parts of the play. Lisa Petterson, as Suzanne's adoring best friend and Allen's greatest detractor, is never able to overcome the character's extraneity to install her as the necessary fulcrum of the action and mirror to reflect the emotional myopia surrounding her.

Samtur hasn't written his play to encourage us to care enough about Petterson's booze-loving friend with a well-hidden secret - he wants to force us to reexamine the most shadowy sectors of our lives that are forever right in front of their eyes. Family Symmetry is at its finest when it focuses its lenses on that, but as currently configured it misses the longer view just a little too often.

Family Symmetry
Running time: 80 minutes
The Jewel Box Theater, 312 West 36th Street, 4th floor
Tickets online and current Performance Schedule: OvationTix