Sincerely, The Duke is the final novel in the historical romance Say I Do trilogy about dukes needing to wed to tap into their wealth.

When the Duke of Hurstbourne receives a letter from his childhood friend asking him to marry his sister Ophelia, Hurst declines. He's not adverse to taking a bride, but he believes in love at first sight that stirs his desire--not marriage sight-unseen.

Adhering to society's strict propriety for ladies, Ophelia Stowe has no choice but to present herself as a man to seek the Duke of Hurstbourne's favor. If not for the dire situation she finds herself in, she wouldn't have asked for help from the handsome man who had rebuffed her. When the alluring duke's response is a plan of his own, Ophelia never dreams it would be a proposal of a marriage of convenience.

But the stakes are high, and the good name of the Stowe family will be damaged if a missing antiquity isn't found. When she accepts his offer, she quickly finds she isn't immune to the passion building between her and her new husband--or how real the marriage begins to feel.