As kids, twins Maggie and Milo were affectionately referred to by their father as "the gruesome twosome." Twenty years later, the nickname seems less amusing.

Milo (Bill Hader), a waiter/failed actor in Los Angeles, writes a clipped, defiant note before slitting his wrists in the tub. Across the country in the small New York town where they grew up, Maggie (Kristen Wiig) is a dental hygienist and cheating wife who's about to swallow a bunch of pills. Her plans to end it all herself are thwarted by a phone call about her brother's attempted suicide.

Such are the similar states of mind for "The Skeleton Twins," an unassuming, emotionally honest little indie that won a screenwriting award at Sundance last winter.

Despite not having spoken to him in a decade, Maggie brings Milo home with her to recuperate and possibly mend their strained relationship. As Milo gets to know her affably earnest husband, Lance (Luke Wilson), Maggie carries on with her scuba instructor (Boyd Holbrook), driven less by lust than by a desperation to escape.

From the start, Hader and Wiig are so convincingly depressed that they don't even look like the same people who cracked each other up playing dopey Devon and Karina in "The Californians" sketches on "Saturday Night Live." The permanent smirks they used to wear here morph into crags, sags and droops on Hader's mug, and a wan wistfulness framed by frown lines on Wiig's.

Lest they drag the audience down too far with them, the film is punctuated with sarcasm — Milo can't wait to be "the creepy gay uncle" if Maggie has a child — and believable bursts of brother-sister silliness. There are scenes that lapse into improv, like when they goof around with equipment at the dentist's office where she works, or he lip-syncs to Starship's "Nothing's Gonna Stop Us Now."

Nothing momentous happens as the twins slouch toward reconciliation. But the script, cowritten by newbie director Craig Johnson (the under-the-radar indie "True Adolescents" is his only other feature) and Mark Heyman ("Black Swan," "The Wrestler"), artfully unfolds to reveal telling nuggets from the siblings' shared and separate histories. A brief visit from their narcissist mother (Joanna Gleason), a self-styled new-age healer living in Sonoma, speaks volumes about the love and guidance missing from the twins' upbringing.

Maggie is a restless dilettante, always picking up new hobbies as an excuse to pick up something else. Milo's reconnection with his former high school English teacher (Ty Burrell of "Modern Family," also cast against type) is tinged with neediness, by turns touching, pathetic and dark.

While inferences abound, the reason for the twins' 10-year rift is kept under wraps until Halloween night, when they dress up their bods and peel back their facades. "The Skeleton Twins" is quietly smart, sweet but never syrupy. It should erase any doubt that its two stars, who rose to success as cut-ups, also have dramatic chops.

Kristin Tillotson • 612-673-7046