Meet Me at Dawn (1947)

A young man makes his living in Paris in 1900 by fighting duels on behalf of other parties. He is hired to injure a leading politician and starts to get involved with a girl he uses to provoke the challenge. One newspaper, hostile to the politician, headlines the story of the impending duel asking who this Madame X is. Problem is, she is in fact the daughter of the paper's proprietor if only he knew it.