By Francis Agnoli

A woman in a blue dress walks through a rain-soaked field. She is no longer young but not yet old. Comfortably middle-aged. The type of woman who looks like she is expecting her first grandkid. The camera glides around the woman, and she  starts to dance. A series of emotions cycles across her face. Detachment. Happiness. Sorrow. We don't know why she is dancing. We do not know who this unnamed woman is. The title labels her "mother." That is all we know.

From director Bong Joon-ho (Snowpiercer), Mother focuses on the relationship between its anonymous protagonist (Kim Hye-ja) and her mentally disabled adult son, Do-joon (Won Bin). Despite some unresolved tension below the surface, the two are very close. They only have each other, and she would do anything for her son. When Do-joon is arrested for the murder of a high school girl, his mother stops at nothing to clear his name and find the true killer. What follows is a series of red herrings, twists, and character revelations that will leave any fan of Hitchcock satisfied. To say more would be to ruin the experience.

The reference to Hitchcock is not careless namedropping. An expert in the man-wrongly-accused subgenre, he was also known to delve into the rich and often disturbing field of mother-son relationships. Had he been born in a different time and place, one can imagine old Hitch directing a film akin to this one.

With discussion of the plot off-limits -- rest assured, the ending is both surprising and inevitable -- let us turn our attention to other matters. As the titular mother, Kim Hye-ja is perfect. There is not an ounce of glamour or vanity about her. She is a woman who has long ago devoted her entire existence to the wellbeing of her son. I write not about physical appearance or clothing -- both are appropriate for the character -- but of her attitude and actions. The script requires Kim to go to some emotional and even physical extremes, and Kim is more than up for the challenge.

Of course, to give sole credit to the performer would be a mistake. Director Bong Joon-ho expertly keeps the audience at just the right distance from his protagonist. He will frame her in sympathetic close-ups. But, for key scenes, he keeps her in profile, shot with a telephoto lens. In doing so, Bong hides his character's emotions. He makes especially good use of this technique in a bookend to the opening dance. We never get the full picture.

In a time when thrillers -- especially those imported from South Korea -- are noted for their gratuity, it is a relief to find one with such restraint. It is violent, but significantly less so than Oldboy (Park Chan-wook, 2003) or I Saw the Devil (Kim Jin-woon, 2010). Gore enthusiasts will probably be left unsatisfied. However, Bong understands perfectly how much he needs to show and how much he can hide, sometimes within the frame. It takes courage to shoot the climactic murder through a dirty window, and it takes skill to make that shot work.

As a Hitchcockian thriller, as a star vehicle for Kim Hye-ja, and as an exercise in plot and style, Mother simply succeeds.