At age 16, Gabrielle finds letters written by her father which prove that his crime had been instigated and aided by a body of noble gentlemen, who planned it as warning to the King to change his ways.

With the evidence of their crime, Gabrielle sets out to confront the Marquis de Saint-Lucque, the only person named in the letters, and succeeds in extorting a large amount of money from him.

Her plans are dashed when Fernand breaks off their affair as the King has decided that the Vicomte should marry his illegitimate daughter, Neve de Nesle.

But she has not counted on Neve's mother, Madame de Nesle, who on hearing of the situation, uses her position as the King's favourite to have Gabrielle, now 19, thrown into prison without trial.

[1] Sally Duggan notes that Orczy invokes biblical language to celebrate Gabrielle's downfall at the end of the book - depicting the Frenchwoman as 'a warning to all assertive females'.