MY FRIENDS keep having babies. The Great Baby Epidemic started about a year ago, and will presumably continue until Portland has been entirely repopulated with white babies named Tallulah. And if I've learned anything from pop culture, eventually one of them is going to be a Bad Seed.

I've never met a Bad Seed in real life, but books and film have been very instructive. They're kids who crawled out of the womb monsters, and they're going to stay monsters, no matter how hard their long-suffering mothers try to change them. Doris Lessing's deeply disturbing short novel The Fifth Child is a classic example. 1993's The Good Son, starring eeeevil Macaulay Culkin. (Fun fact: written by Ian McEwan!) And of course, the tiny blonde killer from 1956's The Bad Seed itself. These kids are proof that evil exists in the world, or at least that their mothers should've tried a little bit harder.

The newest film from hotshot Xavier Dolan (Heartbeats, Laurence Anyways) somewhat complicates the bad-seed archetype: Steve (Antoine-Olivier Pilon) is a bright, charismatic teenager prone to fits of recklessness and rage. His official diagnosis is "ADHD and attachment disorder," which translates to "violent outbursts and occasionally pawing Oedipally at his hot mess of a single mom," Diane (Anne Dorval). Diane is devoted to Steve, but lacks the financial and emotional wherewithal to truly give him the care he needs. And Steve himself is both light and dark, struggling against his own worst impulses. Most Bad Seeds don't love their mothers; Steve loves his a little too much.

Mommy opens with a framing device that suggests we're about to watch some near-future dystopian riff about the police state-ification of parenting: In Montreal in 2015, we're informed, a new law was passed permitting parents to institutionalize their children for any reason. This information has virtually no impact on most of the story or on the present-day Quebec setting. It's simply the filmmaker showing his hand—less an experiment in world building than a hasty retrofitting of the world's rules in order to accommodate the high stakes of the plot.

That plot is mostly about Diane's desperate attempts to care for her kid, who can be sunny and charming one moment and violently aggressive the next. After Steve sets a fire at the youth facility where he's been living, Diane has a choice: have him committed, or bring him home. She brings him home and enlists her mousy, stuttering neighbor Kyla (Suzanne Clément) to help with his education. The three form a disjointed little band of outsiders, their morale soaring and plummeting according to whether Steve is having a good day or a bad one.

The mood of Dolan's film shifts as violently as Steve's, going from sunny, Oasis-soundtracked optimism to frightening violence. Not content to manipulate his audience with a '90s soundtrack alone, Dolan plays with aspect ratio, boxing his characters into perfectly square 1:1 aspect ratio in darker moments, cracking the frame open to widescreen to let in moments of light and optimism.

The three leads give beautifully dense performances; Anne Dorval, in particular, lends her character a ragged optimism, never giving up on Steve even when audiences might think that she definitely should. Maybe Mommy isn't about a Bad Seed, after all: Maybe it's about how far a mother's love can—or should—be pushed.