The Masqueraders (English, Paperback, Georgette Heyer)

Prudence and Robin Tremaine, are children of the notorious and brilliant Viscount of Barham, find themselves on the wrong side of the Jacobite rebellion. The brothers have been dissemblers since they were children. And in this age of slippery politics, they need to be. Their infamous adventurer father has taught Prudence and her brother Robin to be masters of disguise. To escape detection, the Viscount sends his offspring on the road to London, each masquerading as the opposite sex. Prudence pretending to be a dashing young buck, and Robin as a lovely young lady.

During the travelling to London to meet their eccentric and rather wayward father, they take a break for a meal, and overhear what is clearly a reluctant elopement… and decide to get involved. It quickly becomes clear that the brother and sister are not exactly what they seem to be… For they it is nothing to rescue the charming Letitia Grayson, a rich heiress from her abductor. But once committed to their masquerade, they must see it through. And now, with their own Iives at stake, they hid in the very limelight of London society.

As Peter Merriot, captivating Prudence became the favorite companion of dashing and elegant aristocrat Sir Anthony Fanshawe, her guise that become highly inconvenient when she falls for him, even though discovery of her true identity meant death. Just as it seemed as though her mad pose might succeed, she was challenged to a duel. Prudence knew it would not he long before this tall, sleepy-eyed gentleman fathomed her desperate secret. The two masqueraders must find a way to unmask themselves without losing their lives
Source – Goodreads.com
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