Never a Duchess by Adele Clee

She refuses to be any man’s wife, let alone a duchess.
Having suffered a wicked betrayal, Miss Lillian Ware cannot trust anyone, least of all the scoundrels roaming the ballrooms. Indeed, what better way to help naive debutantes than to write a book detailing how one might spot a rogue? Gathering information is a dangerous game, especially when a certain duke discovers her secret.

A scandalous offer from a duke.
For five years, Callan Maclean has scored his name on Miss Ware’s dance card. For the last three years, she has disappeared before he can claim his dance. But when he finds her spying on the ton, he offers another suggestion. He will educate her in the ways of a scoundrel himself.
But matters take an unexpected turn when they witness an abduction and feel compelled to investigate.