The doting Baron de Tortillee marries the lascivious and extravagant Mademoiselle La Motte, who promotes the villainous Du Lache to be the instrument of her vile pleasures. After enjoying several lovers of his procuring, she fixes her affections upon the worthy Beauclair. Du Lache despairs of ensnaring him, because he is about to marry the lovely Montamour, but by a series of base expedients he manages to blacken the character of that lady in her lover's eyes, and to put the charms of the Baroness in such a light that Beauclair is at length drawn in to pay his court to her. For some time she thus successfully deludes her husband, but when the despicable La Branche openly boasts of her favors and allows some of her letters to fall into the hands of one of her numerous lovers, her perfidy is soon completely exposed. To add to her confusion she hears that the Baron, whom she had drugged into idiocy and sent into the country, has been cured by a skilful physician and is about to return. Du Lache despatches two assassins to murder him on the road, but the Baron by a lucky chance escapes the murderers, forces them to confess, and sets out to punish his guilty wife. Meanwhile Beauclair suspects that he has wronged his innocent lady and endeavors to see her, but she at first refuses to see him, and when by a ruse he gains access to her presence, will not listen to him or give him any grounds for hope. In despair he returns to Paris and meets the young Vrayment. He discovers the infamous Du Lache hiding in a convent. To save his life the wretch offers to reveal the frauds he had put in practice against Montamour, but while he is doing so, the Baron meets them, and concluding that Beauclair is in collusion with the villain, attacks them both. Beauclair disarms his antagonist and is about to return him his weapon, when Du Lache stabs the Baron in the back. Vrayment has witnessed the quarrel and summoned assistance. Beauclair and Du Lache are haled before a magistrate and are about to be condemned equally for the crime, when Vrayment reveals herself as Montamour disguised as a man, and persuades the judge that Beauclair is innocent. Du Lache and his accomplices are broken on the wheel, the Baroness takes poison, and Beauclair is united to his faithful Montamour.