Xavier Dolan's Mommy is an endurance test even by the standards of miserablist drama, a non-supernatural monster movie whose vision of a seriously dysfunctional relationship between a mother and her child makes The Babadook look that much better. Diane (Anne Dorval) is a widowed mother whose teenage son Steve (Antoine-Olivier Pilon) is the picture's monster, an ADHD-riddled hellion who can go into a violent rage at any moment. Director Dolan never shies away from the pornography of those moments, making them all the more claustrophobic by shooting all but a few scenes within a square frame, narrower even than the 1:33 aspect ratio of pre-widescreen film and television. Eventually entering the cramped picture is the good-hearted Kyla (Suzanne Clément), a neighbor and stuttering former schoolteacher who neglects her own husband and daughter to help Diane deal with Steve. The actors are all clearly committed to their roles, not so much rising above the material as jumping in headfirst and wallowing, probably the only way to make it work. Mommy has some troubling themes about single motherhood — Steve's problems began after his father died — and its portrayal of broken teenage masculinity has shades of The Place Beyond the Pines, though some might argue that looking at it from that point of view means you're the monster.