Miss Harriet Redgrave, a horrendously rich American heiress, laughs too loud, states her opinion directly, and even conducts science experiments. Her grandfather is desperate to get her off his hands and is offering a king's ransom to anyone able to arrange a suitable marriage that comes with a title. To avoid marriage, Harriet swears off all men, until she meets Duncan Maclachlan, Earl of Thornton. But when Thornton is falsely accused of being a traitor, Harriet must use her knowledge of chemistry to find the real culprit and spark true romance.

Heiress Harriet Redgrave resists her grandfather's intentions to marry her off to a lord until she meets Duncan Maclachlan, Earl of Thornton, who worries that her American upbringing has ill-prepared her for English high society.