A well-crafted drama can frighten as much as any good slasher flick. I think one could even argue that there’s already a distinct genre out there populated by dysfunctional families, deeply unsettling metaphor and shockingly unconventional violence. Claustrophobic, sporadically bombastic, and chillingly understated, these living room thrillers are often initially quite divisive yet often seem to find longevity. “Dogtooth” comes to mind, along with “Who’s Afraid of Virginia Woolf?” Zaida Bergroth’s “The Good Son” is one of these films. Ilmari (Samuli Niittymäki) is a dangerous teenager with more than typical family responsibility. His mother, the actress and tabloid target Leila…...