Xavier Dolan’s riveting dark comedy explores the tumultuous relationship between a widow trying to hold on to her youth and her hyperactive and sometimes violent teenage son. Help comes in the form of a new neighbor, a seemingly timid former schoolteacher battling a stammer as well as her own demons. Together the unlikely trio traverses the unpredictable and bramble-strewn world of parenting. Winner of the Cannes Film Festival 2014 Jury Prize, “Mommy” defies modern, splashy, big-screen tropes: there are explosions, yes, but they come from the performances and the film’s brilliant cinematography, which immerses you in private moments of pain and joy in the most unexpected and revelatory ways. It’s outrageous, it’s brilliant, it makes everything else around look negligible and passionless. Don’t miss “Mommy.”