If writer-director Sebastián Silva’s Nasty Baby stuck to its Sundance-friendly story—the trials and tribulations of a gay couple and their best lady friend, readying to carry their child—it would deliver authentic warm and fuzzies. It would win audience awards. It would quietly buzz through the festival. It would fade out into the long history of Brooklyn-set indie dramedies. It’d be nice.

Nasty Baby is not that movie. Thank God.

Since Bridesmaids made box-office bank and imploded comedic expectations, Kristen Wiig has embraced independent films that allow her to play weird, weirder, and weirdest (see: the impossible-to-log-line Welcome to Me). Nasty Baby brings the actress back down to earth . . . though Silva’s surrounding atmosphere compensates in the quirk department.

Freddy (Silva) is a visual artist dying to be a father. His BFF Polly (Wiig) is more than happy to assist in the pregnancy. The only problem: Freddy’s sperm isn’t doing the job. So it’s up to Freddy's boyfriend, Mo (TV on the Radio’s Tunde Adebimpe), who’s reluctant to go through with the insemination. Nasty Baby rambles along with their sometimes cheeky, sometimes intimate conversations, the movie tightrope-walking above a twee hellmouth like it’s Nik Wallenda. Freddy and Polly take pictures with stranger's babies to woo Mo. Mo distracts himself with his plant collecting. Dinners with friends and family complicate the situation, everyone from Freddy’s stoner brother to Mo’s subtly homophobic sister weighing in with opinions. All the while, Silva, Wiig, and Adebimpe offer more charm than the screen can handle.

Nuzzled between all the sweetness is an arsenal of Chekhov's guns. Freddy is a control freak, frustrated that the block’s resident kook spends his Saturday mornings cleaning the sidewalks with his thunderous leaf blower. Anyone from New York recognizes the character of Bishop, an overly aggressive, not-quite-there staple who can go from eccentric to offensive in the blink of an eye. Freddy doesn't care for his slur-filled beat poetry. But life moves on, the baby issue trumping everything. Through vibrant music cues and a marijuana-scented cloud mellowing the scenery, Silva averts the movie’s occasional dangers to concentrate on more grounded problems. Polly’s determination, Mo’s contemplative zen state, and Freddy’s playful banter defy movie conventions. They’ve got everything under control but their own psyches.

Or, they think they do. Nasty Baby will likely go down as 2015’s greatest “shit happens” movie. There are red herrings planted to spook us: during a last ditch effort to use Freddy’s sperm, we see Polly pour out the semen sample into a nearby planter. Has she been sabotaging the efforts the entire time? Not quite. Later, Freddy visits a gallery owner to show off his latest art installation, a video compilation of him and his friends crying like babies. The project baffles the curator, but he leaves it to “the oracle” to decide Freddy’s fate. What follows is major spoiler territory, anything but predictable and, for many people, anything but logical. Silva creates a world where no amount of planning can prepare his trio for life’s curveballs. To tease: Nasty Baby’s last 30 minutes should give Breaking Bad fans flashbacks (and not just because Mark Margolis plays the couple’s downstairs neighbor).

Silva’s off-the-cuff style suits Wiig, who delivers her best performance since Bridesmaids. Same goes for Adebimpe, who taps the same impressive sensitivity on display in Rachel Getting Married. Nasty Baby is all about likability, delicate stained-glass drama ready to be shattered by Silva’s cruel curiosity. The rare film that will actually make you laugh, make you cry, and leave you hyperventilating in its final moments.