Harriet, Duchess of Berrow, has been rusticating in the country, dispensing her version of justice to the people of her county seat. Widowed two years before when her husband committed suicide, she is ready for a change. Opportunity is presented when her friend Isadore decides to lure her absent husband home (see When the Duke Returns) by visiting an scandalous house party hosted by Lord Justinian Strange. Two noble women cannot just go alone, so Harriet becomes Harry, a young mama-protected cousin of Villiers, (see Duke of Her Own). Strange find himself strangely attracted to Harry. And Harry finds herself attracted to him too. But with the Harry's male persona, Strange is fighting it. James is wonderful at weaving in characters from her other books.
3rd in the Desperate duchesses series.
Duchess by Night / Eloisa James 384 p.
If you like Mary Balogh, try Eloisa James. For the Desperate duchesses series start with Desperate duchesses.