Drake, Olivia. Cinderella Sisterhood novel.

"Bella Jones feels like a fish out of water in civilized England. Raised abroad by her explorer father, she's amused by the very proper manners of the nobility. Nevertheless, to save her younger siblings from ruin, she must infiltrate a ducal household in order to find the map to an ancient treasure trove. Alas, the haughty, handsome duke stands in her way...unless she can tame his beastly temper, that is. Miles Grayson, the Duke of Aylwin, prefers antiquities to, well, everything else. Especially prying females with their irksome questions. But Bella's blue eyes and beguiling smile are improbably charming, and the temptation of her kiss is impossible to resist. As the pair is swept into a mystery that reaches back to their childhoods, Miles realizes that Bella has made the rarest discovery of all-the key to his heart" --