When a couple of thirty-somethings let the mother of one of them cross the threshold into their home, they have no idea that they have just entered a kind of purgatory. Their peaceful life is slowly transformed into a chaotic wreck. Valerie, a well-groomed woman in her sixties, is an energetic diva who little by little conquers not only the space of the apartment, but also the minds of its occupants. As the creeping home invasion gains force, certainties are undermined and the boundaries of privacy are demolished. Are moms and mothers-in-law always right? Do they have good intentions toward us? And isn't that why they are the scariest monsters of them all?