"WELL, I'M SURE he had his reasons," says Crystal (Kristin Scott Thomas). Crystal is fake-blonde and rich and old and mean; like everyone else in Only God Forgives, she's also terrifyingly, comically intense as she single-mindedly pursues her goals in the sweaty heat of Bangkok. When she says, "Well, I'm sure he had his reasons," it's in response to learning that her son Billy (Tom Burke) has raped and murdered a 14-year-old girl.

Billy's paid for his crime—a vigilante named Chang (Vithaya Pansringarm) allowed the girl's father to beat Billy to death—and Crystal, cold-eyed and colder-hearted, now wants vengeance for her son's death. Good thing her other son, Julian (Ryan Gosling), is also in Bangkok, where he lives off the family drug-running business, teaches at a Muay Thai school, and visits his prostitute girlfriend, Mai (Yayaying Rhatha Phongam). Tasked by his mother to avenge his brother, Julian starts digging even further into the grimy, beautiful hellscape of Bangkok's underworld—putting himself on an inevitable collision course with Chang, whose righteous cruelty might prove more than either Julian or Crystal can handle.

Only God Forgives is Nicolas Winding Refn's follow-up to 2011's very nearly perfect Drive, and it is very far from perfect. If one element of Drive stuck in audiences' memories, it was its hazy, druggy atmosphere: Gosling, then a nameless driver, staring into the distance, or gazing lovingly at Carey Mulligan, when he wasn't dispensing righteous bursts of violence. In Only God Forgives, that equation has been switched; whether Julian or Chang is the instigator, the violence takes the forefront and is usually the opposite of righteous. Going for levels of horrific gore and lurid blood that he hasn't reveled in since his Pusher trilogy, Refn zooms in, tighter and tighter, on his characters' psychological and physical mutilations. A friend I saw Only God Forgives with described the experience as "excruciating." I didn't offer a defense.

That said—at least for those who're fond of Refn's work, which also includes Bronson and Valhalla Rising—Only God Forgives isn't without a few pleasures. Few filmmakers allow their neuroses to splatter the lens as obviously as Refn—for better or worse, he goes for broke, and what starts as a vengeance movie soon becomes one of the more fucked-up family portraits in recent memory, marinating in blood and failure and not-very-subtly-implied incest. Only God Forgives also offers moments of visual beauty and strange, uneasy humor, not to mention another excellent score by the best film composer working today, Cliff Martinez (who's having a pretty great 2013, given this, his score for Robert Redford's The Company You Keep, and his Spring Breakers collaborations with the gentleman we've come to know as Skrillex). Towering above everything and everyone else, though, is Kristin Scott Thomas, whose sadistic, conniving Crystal is a magnificent addition to the cinematic canon of eeeevil mothers. When she dines with Julian and Mai—and methodically, cheerfully, and heartlessly proceeds to tear both of them down, leaving them ruined husks—it's one of the most brutal scenes in Only God Forgives. Given the rest of the movie, that's a pretty remarkable achievement.