Starring Catalina Saavedra. Unrated. Plays Friday and Sunday, May 28 and 30, and Wednesday to Thursday, June 2 to 3, at the Vancity Theatre

When The Maid begins, you get set to watch an intimate portrait of upstairs-downstairs politics, with an upper-class Santiago family awkwardly attempting to throw a birthday party for their servant of 20 years. Then, as you get to know the maid in question, turning 41 but looking a decade older and carrying a lifetime of seething resentments, you wonder if this will turn into a horror movie.

Eventually, though, the film wanders into dark comedy, thanks to a masterful performance by Catalina Saavedra as the hard-bitten Raquel, and the sly hand of writer-director Sebastián Silva. Both won major awards at this year’s Sundance festival. Silva is only 30, and he shot The Maid in his own family home, basing its story on dynamics familiar to him.

The director’s younger brother, Agustí­n Silva, plays the Valdez family’s teenage son, the apple of Raquel’s eye. The taciturn housemaid has no love for the boy’s older sister (Andrea Garcí­a-Huidobro), and tortures her accordingly. Their mother, a mild college professor (Claudia Celedón), is too paralyzed by guilt or dependency or something to loosen Raquel’s stranglehold on the family. (Apart from the Chilean class aspects of the tale, this is one uncommunicative clan, and their servant knows plenty of things they hide from each other.)

In any case, our grim-faced protagonist has zero life outside that house. (On her day off, she skulks around the edges of the middle class, buying a sweater just like her boss’s.) And when this unhealthy arrangement takes a visible toll on her health, the Valdezes insist on bringing in new help, with increasingly disastrous results. Only when they luck into a lovably daft young woman (Mariana Loyola), whom Raquel can’t bully, do events turn around, and this wonderfully satisfying movie—like its namesake—finds a beating heart beneath the starched white collar.