its a variation on Battle for the Cowl. in the real arc, Batman is "dead", and a murderous, new Batman appears. this draws Red Robin and Nightwing into town in part to investigate along with Damien Wayne [Robin]. IIRc this was the last big arc before the new 52. at teh end of it all, Nightwing defeats the impostor once and for all after Red Robin takes on grave injuries, and by persuasion by Alfred, becomes Batman