"Who is this new Batgirl who seems to have taken over my crime fighting territory?" - Batman
Why, she is a librarian, you caped crusader with a dark side. Came across this amusing article about a surprising former librarians on mental_floss today, and was most interested in #10 in the list - Batgirl.
"When the comic wanted to generate female interest, a “grown-up” version of Batgirl appeared in January of 1967 in Detective Comics #359. In this later incarnation (the original, Bat-girl, was created in 1961), Barbara Gordon was the grown daughter of a Police Commissioner and worked as a librarian. She only began her crime-fighting career by accident, breaking up a robbery when she happened to be wearing her Halloween costume. Who was the victim of this crime? Bruce Wayne, of course!"
According to the DC Comics database, she was delivering a rare book to Wayne Manor when she broke up the robbery. A cautionary tale. Don't mess with a bibliophile.