The basic plot is as follows. Louisa Darwen's family died while overseas in Turkey; a Sultan adopted her (as he liked her and her family). She was raised in the harem, learned Turkish and the religion of the Muslims, and now is returning to England to take up her inheritance (such as it is).
Gervase, Earl of Coldmeece, is an unusual fellow. He's thirty-five, still unwed, has an unusual, strange sense of humor -- and dislikes Louisa without even meeting her, because of her unusual background.