The Lady in Pearls by Lauren Smith

After Daphne Westfall’s father is convicted and imprisoned for forgery, she is turned out onto the streets of London during a particularly cruel winter. Owning nothing more than her late mother’s pearl necklace, Daphne’s only hope of survival is to take her chances at a marriage auction.
Lachlan Grant, Earl of Huntley, wants revenge against the counterfeiter who drove his brother to suicide. When he discovers that Westfall’s daughter is selling herself into marriage, Lachlan knows he’s found the perfect revenge. But Daphne Westfall isn’t the spoiled brat he expected to marry, and on their journey north to Scotland, he learns that exacting revenge upon another innocent victim of Westfall’s crimes is beyond his capability. As respect and affection turn into love, Lachlan tentatively imagines a future free of pain and loss. That is, unless Daphne learns that their engagement was built upon a foundation of revenge.