Hmm... Are you talking about the book or the film?

If the latter, your task would be considerably simplified by the fact that the script can be found online in this sort of format:

RHETT: I'm going to Charleston. Back where I belong.
SCARLETT: Please, please take me with you.
RHETT: No. I'm through with everything here. I want peace.
I want to see if somewhere there is something left in life with charm 
+and grace.
Do you know what I'm talking about?
SCARLETT: No. I only know that I love you.
RHETT: That's your misfortune.
SCARLETT: Rhett! If you go, where shall I go? What shall I do?
RHETT: Frankly my dear, I don't give a damn.
[download]

(But then you would still have to determine whether a given line by e.g. SCARLETT is part of a conversation with RHETT, or with somebody else, or a monologue, or whatever...)

And if the former, frankly, my dear, you have a big problem: parsing the text of a book for conversations between given characters is not a task for a beginner (in Perl or any other language).