The Girl with the Pearl Pin by Lynne Connolly

Founded by the wealthiest woman in London, an unconventional crime-solving club brings together single lords and overlooked ladies from every rung of society. It’s a perfectly scandalous match …

As London’s most sought-after bachelor, the Duke of Leomore stuns society when he announces his engagement to a woman who has just been branded a thief. Yet as his painfully shy “bride-to-be” understands, it is merely a ruse until The Society for Single Ladies apprehends the true culprit—and a ploy to further delay Leo’s obligation to wed. For him, marriage will be a purely practical affair. Still, why does a stolen kiss with his faux fiancée conjure such tempting visions of romance?…

As if being falsely accused weren’t mortifying enough, Phoebe North is now the talk of the town. And while she knows Leo did the honorable thing to protect her reputation, she can’t help but long for more. It would be an impossible match given their unequal stations, and Leo has made his view of marriage quite clear. Yet his kiss and flirtatious ways say something else. If only she could persuade him of how delightful it would be to thumb their noses at convention—and become fools for love…