Noel Annequin's (Fernandel) dying wife begs her husband to put her out of her misery. He does so, then confesses his crime to his three brothers, all pillars of the community. Pursuing their own selfish agendae, the brothers cart their sibling off to a lunatic asylum. Only Noel's niece Martine (Jeanne Moreau) remains loyal, and it is Martine who sets the wheels in motion for a happier ending than the audience has been conditioned to expect. Incidentally, the title is ironic: as the plot unfolds, the viewer realizes that Noel's hypocritical brothers are the real sinners of the piece.