How does Marguerite Blakeney try to stop Chauvelin in The Scarlet Pimpernel?

The French Revolution is reaching its bloody apex, and Marguerite St. Just, or Lady Blakeney, has fallen into the grip of a French spy named Chauvelin. He has demanded that she help him find out the identity of the Scarlet Pimpernel or he will order her brother, Armand, executed.
At a ball, Lady Blakeney reveals to Chauvelin that the Scarlet Pimpernel will be in a certain room at one o’clock that night. When Chauvelin enters the room, he discovers Sir Percy, Lady Blakeney’s husband. Before she leaves the ball, Lady Blakeney is again approached by Chauvelin, who again warns her of her brother’s danger.
That night, Lady Blakeney breaks down in front of Sir Percival, revealing her brother’s danger and her decision to help Chauvelin trap the Scarlet Pimpernel. Sir Percival reacts coldly to her but promises to help her brother escape the guillotine.
That night, Lady Blakeney discovers that her husband is the Scarlet Pimpernel and decides to sail to Calais to warn him of Chauvelin’s trap.
Lady Blakeney goes to an inn and discovers Chauvelin arguing with her husband. Chauvelin leaves and orders his soldiers to arrest Sir Percy, who manages to escape. Lady Blakeney follows Chauvelin, who enlists the aid of an old Jewish man in hunting Sir Percy down.
The Jewish man leads Chauvelin to a hut and insists Sir Percy is inside, along with Armand. Lady Blakeney comes out of hiding and rushes toward the hut to warn her husband and Armand of the trap, only to be captured by Chauvelin.
Chauvelin and his soldiers enter the hut and find it is empty. Chauvelin has Lady Blakeney bound and the old Jewish man beaten up. As his soldiers are roughing up the Jewish man, Chauvelin discovers a note detailing a meeting where the Scarlett Pimpernel will be.
Chauvelin goes to find the meeting, leaving the Jewish man and Lady Blakeney behind. Once they are alone, the Jewish man reveals himself to be Sir Percy and tells Lady Blakeney that Armand is already safe. The two of them sail for England the next day, their love rekindled.