There's a mystery afoot in Gotham City when a shadowy vigilante known only as Red Hood (voiced by Jensen Ackles) sets his mind to stalking Batman (Bruce Greenwood) and his former sidekick, Dick Grayson (Neil Patrick Harris) -- who now goes by the heroic name of Nightwing. But the duo can't get too distracted, lest they fall prey to three familiar nemeses: the Joker (John Di Maggio), Ra's al Ghul (Jason Isaacs) and Black Mask (Wade Williams).