Nightwing: Supercop by Devin Grayson Vol. 1

Dick Grayson, known as Nightwing, finds himself in a precarious situation when a super-steroid turns Blüdhaven's police force into super-powered, murderous maniacs. As the city's protector, Nightwing must uncover the source of this madness and protect the citizens from those sworn to serve them. He faces a chaotic challenge that may be too much for him to handle alone.