Marguerite St. Just is the wife of Sir Percival Blakeney. She is an actress who previously performed at the Comedie Francaise. She was once the lover of Citizen Chauvelin, which Chauvelin threatened to tell Percy if she didn't deliver information on the location of the Marquis de St. Cyr. She is sister to Armand St. Just, who she loves more than anyone else. When Armand is captured in France, she makes her way to France to rescue him. Over the course of the musical and the book, she is blackmailed by Chauvelin to tell him the location of the Scarlet Pimpernel. She is confused by Percy's foppish manners after he must pretend to be a fop to disguise the fact that he is the Scarlet Pimpernel, which he keeps from Marguerite. This leads to some unhappiness in her marriage, and it causes her to believe that her husband does not love her.