The genius of Sebastián Silva's second film – winner of the World Cinema Prize at Sundance 2009 – rests in its steadfast refusal to bow to the demands of genre. Introduced to the moneyed Valdes family and their wild-eyed, intense-tempered housemaid Raquel, we might initially be looking at a campy melodrama (disturbed social inferior over-attaches to middle-class dream family) or a horror film (disturbed social inferior over-attaches to middle-class dream family, with bloody consequences). But Silva's film has a surprise in store: it refuses to sell out its compellingly peculiar anti-heroine for an easy plot twist. Certainly Raquel (Catalina Saavedra) takes no prisoners upon her introduction – or in fact does exactly that, responding to the family's efforts to bulk up the house staff by oppressing new domestics with a battery of mistreatment. The determination not to be outdone in the obsessive execution of her work initially brackets her as a comically needy lost soul whose reign of petty terrors must surely be halted and punished, or else a class warrior embarking upon a Genet-inflected inversion of power structures. Yet Silva slyly, sweetly overturns expectations. As Raquel's frantic assertion of control brews chaos in the household, she gradually emerges as a complex and desperately sympathetic character. The first additional maid enlisted by the lovely but ineffectual Señora Valdes (Claudia Celedón) is seen off in no uncertain terms: Raquel locks her out of the house and frames her for kitten-murder. Maid number two fares little better. But when earthy, confident, outspoken Lucy (Mariana Loyola) braves the position, something happens: Raquel's aggression is met with limitless compassion and positivity, and – quite against her will – her barriers against the world begin to shift. For such a guarded and suspicious woman, this is by no means a comfortable process, and here Saavedra's exquisite performance really hits its stride. Raquel's stiff body language begins to soften, and a vast and poignant need for human contact bubbles to the surface. It's an extraordinary portrait of transformation, one that keeps its audience on tenterhooks. Will Raquel's new vulnerability overwhelm her? Will she be betrayed, or succumb once more to the anger which has driven her for so long? Silva's film makes personality the site of utterly compelling and unpredictable drama, with riveting results: funny as Almodóvar, creepy-strange as Buñuel, and with a hopeful, humane heart to boot.