When it comes to Dana, the main character in “La Mala Noche,” there are things you can tell just by looking at her: Dana’s wardrobe suggests that she is a prostitute, while her behavior — interpreted by actress Nöelle Schönwald — reveals her experience, from the way she talks to her more hesitant clients to the manner in which Dana banishes tension to arrange her features into a simulation of inviting intimacy before another anonymous hotel room door opens. And yet, in Gabriela Calvache’s brittle, bleak feature debut, that veneer of self-controlled professionalism masks deepening desperation.

Dana is in debt to her despicable ex-lover Nelson (Jaime Tamariz), now a local kingpin with a sideline in trafficking children into sex slavery. Dana’s beloved but estranged young daughter needs expensive medications and Dana herself has a burgeoning drug addiction, depicted, with the same forensic remove as the sex scenes, in a queasy toe-injecting sequence.