The Skeleton Twins Bill Hader, Kristen Wiig, Ty Burrell. Directed by Craig Johnson. Rated R. Opens Friday.

Anyone expecting The Skeleton Twins to be a zany comedy—not an unreasonable assumption, given that it stars former Saturday Night Live cut-ups Bill Hader and Kristen Wiig—will be disabused of that notion in short order, as the film begins with both of its main characters preparing to commit suicide. Maggie (Wiig) has a handful of pills ready to swallow when she receives a phone call from a hospital informing her that her brother, Milo (Hader), to whom she hasn’t spoken in 10 years, is in stable condition after slitting his wrists in the bathtub. Though their relationship still seems fractious, she invites him to stay with her and her husband (Luke Wilson), upon whom she’s cheating with her scuba instructor (Boyd Holbrook). Not to be outdone, Milo immediately seeks out the former English teacher (Ty Burrell) with whom he’d had an affair when he was only 15. Equally damaged and lost, these twins can only depend upon each other; were they fans of a very similar film by Kenneth Lonergan, they might even say, “You can count on me.”

Directed by Craig Johnson, who co-wrote the screenplay with Mark Heyman (Black Swan), The Skeleton Twins works a bit too hard to explain the title characters’ emotional problems, alluding repeatedly to a father who killed himself and trotting out a cold, loveless mother (Joanna Gleason) to boot. When it sticks to the present-tense relationship between Maggie and Milo, however, it’s as rich a dual character study as the movies have seen all year, beautifully capturing the jagged push-pull of siblings with a long history of mutual dependence and resentment. Both actors do superb work in roles that are almost exclusively dramatic, with Hader a particular revelation as the perpetually wounded Milo, whose defensive sarcasm occasionally gives way to heartbreaking, childlike naïveté. Indeed, it’s a bit jarring when Maggie and Milo engage in a goofy lip-sync performance of Starship’s “Nothing’s Gonna Stop Us Now”—it’s a very funny scene, but it seems to belong in a different movie altogether. This one handles pathos deftly enough not to require the comfort of comic relief.