The Duke's Deception — Fenella Miller

Regency romantic adventure
64 000 words
Previously published as A Dissembler by Robert Hale

Marianne Devenish arrives in Great Bentley expecting to find her great-uncle in residence. Instead she finds The Duke of Wister, Theodolphus Rickham pretending to be Sir Theodore Devenish, a tulip of the ton, more interested in the cut of his coat than in politics.
Unable to stay in a bachelor establishment she moves to Frating Hall, with the permanently impecunious Lord and Lady Grierson. She discovers, to her horror, that Charles, and his younger brother, Edward are involved with the local smugglers.
Theo's dissembling inevitably leads to misunderstandings and heartbreak and with her reputation in tatters Marianne flees to London. But she is ostracised by society and is obliged to find refuge at Drayton House, a small estate in Hertfordshire. Here her life turns into a nightmare.
Can Theo catch his spy, save Edward and Charles from the gallows and rescue the woman he loves before she is lost to him for ever?