Barbara found an opportunity that would ultimately change her life forever. The Gotham City Police Department decided to host the Million Dollar Masquerade Ball at the Bristol Country Club. Dozens of Gotham City's most affluent leading citizens, including the likes of Bruce Wayne and J. Devlin Davenport, were expected to attend. Barbara sewed a stylish, feminine version of Batman's costume based upon designs that she first conceived as a child. For the most part, she intended on crashing the party as this "Batgirl" merely to spite her father.
When she arrived however, she found that somebody else had decided to crash the party before her. A costumed criminal named Killer Moth and his cronies raided the country club, grabbing Bruce Wayne as a hostage. It was their intent to rob the charity proceeds as well as extort hundreds of thousands of dollars from Gotham's wealthiest patrons.
More on this character soon, read the character's bio here: