In 2006, director Bong Joon-ho brought “The Host” to the world stage. A clever, startling reawakening of the monster movie genre, the film brought the director tremendous, well-deserved success, making him something of a master of the genre after only a single picture. “Mother” returns Bong to familiar cinematic ground, taking on a slightly comic, utterly transfixing murder mystery that pins violence and messy displays of injustice on the most saintly of screen images: dear old mom.

Desperate to keep her moderately mentally challenged son Do-jun (Won Bin) out of trouble, Mother (Kim Hye-ja) observes his daily life from her area of work, shooing him away from problematic characters, hoping his better judgment will one day reveal itself. When a local girl winds up gruesomely murdered and displayed for everyone to see, the local police arrest Do-jun in connection to the crime, goading him into a confession. With Do-jun in prison, Mother sets out to find clues that will set her one and only child free, with the help of her son’s friend, Jin-tae (Jin Ku). Hoping for easy answers, Mother instead finds a town of vast dysfunction, with multiple suspects in her pint-sized crosshairs.

“Mother” is a sumptuously Hitchcockian thriller that walks a fine line between wry comedy and broad suspense. It’s a high-wire act from Bong that spotlights his gifts with genre-bending material, unafraid of subtle tonal shifts and stark flashes of horror. While “The Host” was a superb examination of Korean society and environmental damage, “Mother” reduces the cinematic scope to more frenzied domestic concerns, stuffed inside of a spellbinding murder mystery the filmmaker sustains delightfully for the two hour running time.

While assembled with expertly designed cinematography that extracts a delightfully macabre tone out of every available moment, the real power of the film emerges from Kim’s sensitive, trembling performance as Mother. A woman dealing with her own crippling issues of guilt, Mother yearns to protect her son from bullies and scams, watching as her child bluntly bolts through life safe in the knowledge that his mom will be there to catch him when he falls. However, Mother is perhaps Do-jun’s greatest threat, developing a sense of dread that the director coils around the script faultlessly, building the character not expressly on notes of flat-footed sainthood, but of possible sin. Kim’s plays the role to wonderful lengths of worry and desperation; it’s a skin-tearing performance that helps the director find those hostile dark spaces and sublime smacks of revelation.

The twists and turns of “Mother” take on a traditional sense of the unexpected, as Mother inches toward a final revelation that turns a simple declaration of innocence into a winding road of betrayal and deception that threatens to turn the spotlight of guilt on the woman who demanded all the answers in the first place. “Mother” is a true nail-biter, with a generous sense of humor and appreciation for the deranged that maintains an inviting, colorful atmosphere of murder, parental protection, and maternal extremity.

Rating: A-