In a director’s statement circulated by her film’s publicist, writer/director So Yong Kim says Treeless Mountain, which is “inspired by events from my early childhood in Pusan, Korea,” doubles as “a letter to my mother.” This makes the film even more of a heartbreaker––if that’s even a possibility. An autobiographical feature about two tiny girls sent to live with distant relatives by their caring but insolvent mother, Treeless Mountain is a sparse but incredibly moving film about love turning to longing turning to resentment, and if I as a total outsider could barely hold back tears whilst watching it, I can only imagine the strength required to pull such a story from one’s own life and throw it up on a screen.

Jin (Hee Yeon Kim) is a preternaturally mature six year-old who maternally protects her even younger sister Bin (Song Hee) when the two go to live with their alcoholic aunt. The aunt is a cold woman, and something of a shyster. Clearly neither naturally capable nor interested in raising the girls properly, instead of sending them to school she gives the barely post-verbal Bin a bucket and orders her to a neighbor’s house to “beg for salt.” Big Aunt, as they call her, often passes out before cooking dinner, and the girls are left to fend for themselves. In a sad sign of how far they’ve drifted from relative normalcy, Bin and Jin are almost always seen in the middle section of the film wearing the same couple of articles of clothing––a princess play dress for Bin, remnants of her old school uniform for Jin––everything markedly more stained and dingy from scene to scene.

Hands down, the thing that makes Mountain a Toronto must-see is the performances, which are all the more impressive considering the fact that the film’s two young stars are non-actors–––Hee Yeon Kim was found in an elementary school in Seoul City, while five year-old Song Hee was auditioned along with her fellow housemates at a Korean orphange. Hee Yeon Kim’s performance as Jin is absolutely mind-blowing: trudging along with a sadness in her eyes that could only be described as world weary, she’s like a little adult trapped in the body of a girl barely old enough to go to school.

And so she must be. Adults vary rarely let children of this age in on what’s really happening, or why, and so it goes here: So Yong Kim’s camera spends the majority of the film trained in extreme close-up on Jin’s face, so that we can watch the little girl watching the adults and reacting silently to the world around her, and come to our own interpretations at the speed at which the child figures things out. Jin thus becomes not only Bin’s protector when their mother is gone and their aunt is too boozed-up to care, but she also becomes a kind of interpreter, translating what she’s come to realize are the harsh realities of their fate in such a way that the younger sister will have enough information to function, but won’t have to do as Jin has done, and process complications that she’s not ready to understand. So little actually happens in Mountain (and I don’t at all mean that pejoratively) that it would seem a shame to illuminate this more and thereby give away a plot point, but watch for a narrative thread involving a piggy bank. Within this single narrative strand, there’s not an actor in the world who couldn’t learn something about naturalism by watching hope gradually decay into dismay across Jin’s face.