When a group of charming teenagers ring the bell of their high school headmistress (Carmen Maura) with a big bouquet of flowers and a birthday present, we are far from thinking that they are the protagonist of a machiavellian plan.Alice Nabat invites this group of jolly young people to have a drink, not knowing that once the door has closed behind them, they will become her tormentors.What is their purpose? As the plot slowly unfolds and thickens, we learn that they have been cheating in class all year and that they feel more powerful than the "authority" that they are challenging. They actually want to steal the answers to the Baccalaureat (French A Level), to order to pass the precious diploma without any effort on their part.A blackmail of insidious violence happens throughout the night between these "new barbarians" and their terrorized headmistress, hostage to their uncontrolled and threatening actions.