Barbara Gordon (Batgirl) leaves Gotham City to investigate a team known as The Movement. Mistrust on both sides leads to a confrontation in which Batgirl is knocked out.
The Movement plans to unmask her, and in classic fashion does so in a contrived way that allows Batgirl to wake up and escape before her identity is revealed.
Barbara's memories of her traumatic experience with the Joker then sends her into a momentary rage, during which she fights off the members of The Movement.
Source: Digital copy of the comic.