In this taut psychological thriller, a benign real estate deal becomes a sinister standoff between a bourgeois French couple and a dangerous negationist. A Parisian architect sells his flat’s unused cellar to a former history teacher, well-mannered and seemingly normal. When he takes up residence, the stranger’s secret life as an anti-Semitic conspiracy theorist emerges. As the couple struggles to rescind the sale, the increasingly menacing buyer insinuates himself with their naive teenage daughter, turning the family’s idyllic world upside down. Provocative and superbly acted, this nightmare scenario based on a true story will keep audiences guessing from one unsettling moment to the next.