But Kristen Wiig and Bill Hader pull off impressive dramatic range and make for a convincing brother-sister pair in "The Skeleton Twins," a study in depression and familial relations that feels serious-minded without being overly heavy.

The duo star in Craig Johnson's feature, which made its debut in the past week at the Sundance Film Festival and will hit theaters in the late summer or early fall via Lionsgate.

"Skeleton" centers on Maggie (Wiig) and Milo (Hader), siblings from the New York suburbs whose father commits suicide when they’re still teenagers. Now somewhere in their 30s, they still struggle under that weight of that tragedy, he a gay man and wannabe L.A. actor with a few failed relationships under his belt and she a dental hygienist restless in a marriage with a loving but edge-free husband (Luke Wilson). After a failed suicide attempt, Milo comes to live with Maggie in her suburban New York home as the two try to iron out their relationship and their respective lives.

The setup calls to mind similar adult-sibling reunion movies (and Sundance hits) such as "You Can Count On Me" and "The Savages," and if the material here isn't as strong as it is in those films, the two leads give it a freshness and subtlety that make it worthwhile.

In a Q&A after a screening Saturday, Johnson said he had little doubt the pair could handle the roles. "I love comedic actors,” he said. “I'm just drawn to them; I think they're so layered."

He said he's long liked the idea of "recontextualizing" an actor, and cited some of the successful precedents: Jim Carrey in "The Truman Show," Adam Sandler in "Punch-Drunk Love." It seems like a deep list until you realize how many comedians aren't on it. (Incidentally, it's also easier said than done on the financing side; many independent-film backers will balk at the idea of comedy stars in dramatic roles.)

Johnson had Hader on board but hesitated a bit before casting Wiig. “I was worried at first that there was this association, that the ‘Saturday Night Live’ thing might feel gimmicky.”

He went for it anyway, and the move pays off. Not only do the actors have dramatic chemistry, they gin up some good comedy bits as well, particularly in a lip-sync-along from an '80s Starship hit ("Mannequin" nostalgists, take note) and a laughing-gas riff in a dentist’s office. Johnson said he even had to pull things back a little in the editing room so it felt like a brother and sister goofing around, not a couple of seasoned comedians doing their shtick.

Johnson, who wrote the script about eight years ago with classmate and eventual "Black Swan" scribe Mark Heyman, said that he had a close but complicated relationship with his own sister that he wanted to explore.

“Something I wanted to be a part of this movie was brothers and sisters connecting with their secret language,” he said. “No one can make you laugh harder,” but "no one can [tick] you off more.”

As for the actors, well, with Wiig and Hader gone from "SNL" and focused on their movie careers, plenty of offers will await. Let's hope they take more like this.