Elizabeth Dequincy is an orphan who's been caring for an Aunt on the Continent. When she dies, Elizabeth doesn't trust her uncle, so disguises herself as a boy to try and get home to England. She is promptly robbed and then saved by and English fencing master. Thru a series of incidents' "Michael Sommers" has been forced to leave the English military in disgrace as a traitor. However, he was set up by the Brits so he could continue spying for them in Austria, unbeknownst to him. He and "Edward Purcell" room together for a month and she becomes Michael's fencing assistant.
Convoluted story about spies (Nathanson, a Jew and friend) the political situation and Southey's true situation. Eventually he discovers she's female, they fall in love and marry, but not until they're both attacted, Nathanson tortured, Southey beaten, etc.
Must be a sequel to an earlier book to explain all the background & characters.
Pretty clean.