As the Chinese say, Ai-ya! The Grudge and The Ring were but dainty appetizers to the cinematic feast that is this mercilessly disturbing film — director Kim Jee-Woon may just have cemented Asia’s position on the bleeding edge of horror. Shocking in more ways than you’ll ever anticipate, this story of two good sisters and their evil stepmother melds fairy-tale insight into human behavior with the most modern understanding of disturbed psychology to dissect grief and madness with an authenticity that will engage and bewilder both your lizard brain and your higher intellect. The cruelty of Eun-joo (the wickedly good Yeom Jeong-a) to her teenage stepdaughters seems inexplicable: Su-mi (Im Soo-jeong), upon her return home from a stay in a mental hospital, finds her old bedroom full of someone else’s stuff, while Su-yeon (Moon Geun-young), also just discharged, awakens in the middle of the night to find someone creeping around her room. Dad (Kim Kab-su) has withdrawn into his own world — perhaps as a result of whatever terrible event put the girls in the hospital — and fails to believe Su-mi’s accusations of unkindness against his wife. A wildly dysfunctional family is the least of what’s going on, though, and the two ferocious turns the film takes will leave you reeling and fearing for your own sanity. You’ll anxiously jump back in for repeat viewings, eager to uncover answers to the many questions the film’s asks, but answers are maddeningly — and entertainingly — elusive.