THE SKELETON TWINS Pictured above: Not even one goddamn skeleton, let alone two.

IS IT POSSIBLE for estranged fraternal twins to attempt suicide on the same day? Sure, it's possible, but it isn't especially believable. After Craig Johnson, who previously directed the Northwest-set True Adolescents, establishes this credibility-straining premise, The Skeleton Twins finds its darkly comic groove. If it feels like a Sundance Film Festival sensation, in the vein of Personal Velocity or Sunshine Cleaning, that's because it was, and though these small-scale domestic dramas struggle to find paying customers outside the hype-filled bubble of Park City, Utah, Johnson's sophomore effort is better than most.

Kristen Wiig plays Maggie, a dental assistant who lives in Upstate New York with her husband, the kindly if clueless Lance (Luke Wilson), while fellow SNL alum Bill Hader plays her twin brother Milo, a gay actor who moved to Los Angeles 10 years before. Since his agent dropped him, Milo has been working as a waiter. When a breakup sends him over the edge and into the hospital with slashed wrists, Maggie grudgingly invites him to stay with her and Lance.

If Wiig and Hader don't look much like siblings, they bring the same hard-to-fake rapport that made their turn as a married couple in Greg Mottola's under-appreciated Adventureland such fun. And there's fun to be had in The Skeleton Twins, but it floats around the edges of the frame, in the biting dialogue the sarcastic siblings use to hide their pain and the goofy moments they share when not stewing over old grievances.

And make no mistake: This is a film about old grievances. As a teenager, Milo entered into a liaison that made him grow up fast, which can be good for some, but it's infected every relationship he's had since. As for Maggie, she has been keeping a significant secret from Lance throughout their marriage. Instead of telling him and working something out, she sublimates her frustration in an affair with her hunky scuba instructor (Boyd Holbrook). If anything, Maggie is Wiig's least sympathetic character to date, and proves she's ready to go over to the dark side if some enterprising director will give her the chance.

The catalytic agents arrive by way of Milo's former English teacher (Modern Family's Ty Burrell) and the twins' insufferable new-age mother (Joanna Gleason). As screenwriting quirks go, catalytic characters are as much of a hoary device as the neat coincidence of the opening sequence, but I'll be damned if Johnson doesn't make it work.

If the filmmaker falls for the same tricks the splenetic screenwriting guru Robert McKee (played by Brian Cox) promotes in Spike Jonze's Adaptation—"If you write a screenplay without conflict or crisis, you'll bore your audience to tears"—Johnson's strengths as a writer/director come through in the nuanced lines he writes and the multidimensional performances he elicits from his well-selected cast (he wrote the script with Black Swan's Mark Heyman).

Though much has been made of Hader's deft segue to drama, I always believed he had it in him. No, the real revelation is Ty Burrell, who has won Emmys for his sitcom work. His teacher-turned-bookstore-proprietor Rich, about whom I don't want to give too much away, is a decidedly non-comic creation. For all the secrets Maggie and Milo have been keeping from each other, at least they're trying to be true to themselves, but Rich has been living the kind of lie that destroys lives. It's one of those small, subtle performances that evade award recognition, but it's the messy core of this deceptively tidy film.