Hi

I am looking for a historical romance novel. It is the third or fourth among a series, i guess.

The plot is something like this. One of the sisters is engaged to a rather conventional duke bust is in love with another guy, with whom she elopes. The duke is angry and is bent on revenge but then he travels somewhere with the other sister and falls in love with her.

Please let me know if this rings bells for any of you. Appreciate the help.