Hector Loursat, attorney at law, lives with his daughter Nicole in a vast and shabby mansion in this provincial town. They dont talk to each other much, somehow holding the other one responsible for the situation: Hector Loursat used to be one of the great attorneys until his wife left him for another man eighteen years ago. He has been drinking ever since, and given up living altogether, intoxicated every night. Hector did not care much about his daughter, who was brought up by Fine, the old woman servant in the house.One night, gunshots are heard upstairs in the house and Hector spots a shadow running away. Hector goes upstairs with Nicole and finds a dead man lying on an old bed in the attic. The police arrives and investigates. Hector soon finds out his daughter has a kind of secret life with a band of young idle bourgeois from the town: they have regular meetings in the attic.The police soon finds out the dead man is called Gros Louis, with a criminal record. Nicole and her friends are being interrogated by the police. But how is Gros Louis linked to the group? They find out the band of young idle bourgeois have set up in between them a sort of pact, a theft competition which started by stealing a ballpoint or a lighter, and was amplified by boredom up to grand theft auto. They turned delinquants by ennui. The police also finds out that one of them, Emile, is Nicole's boyfriend. Did he kill Gros Louis by jealousy? Emile is suspected, and arrested. In jail, Emile asks Hector Loursat to be his attorney. Hector, scenting a miscarriage of justice, accepts to be his defense attorney.Now is the third act, the trial. The prosecution produces many witnesses of good faith, all bourgeois parents of good faith. Hector Loursat does not bulge, has no questions to asks the witnesses, doesnt seem to be there altogether, to the point where people, and his daughter among them, wonder, with awe, if he is not still drinking. But when finally Hector Loursat stands up and speaks, everyone is bewildered by his speech and strategy. First he does not want any defense witnesses, but wants all the prosecution witnesses to come back to the stand, and accuses all them of being responsible for the boredom of the town, responsible for the boredom and nonsense and stupid behavior of their young ones, then singles out that only one girl - his own daughter, Nicole - was in the group, and, by asking each of the young men, that every one of them was in love with her, except one, Luska. Hector Loursat soon proves Luska was the one most in love with Nicole, that he found out Emile was Nicole's boyfriend, and that he killed Gros Louis to have Emile accused, moved aside and framed. At this rate, Luska cracks up, and is arrested. Nicole falls into her father's arms.