The monstrous Officer Matt Cordell, a towering, undead lawman previously taken down by the NYPD, is revived and continues his vengeance spree against the city's citizens and its police force. Considered long-dead after his incarceration and subsequent brutal attacks in prison, Cordell's murderous rage during his initial killing spree had earned him the label of the eponymous "maniac cop." Despite rumors of his return circulating, most dismiss them as urban legend, causing fear and paranoia to fester within the city. Cordell’s resurfacing is accompanied by a string of violent incidents that hints at his grim intentions to right perceived wrongs and finish unfinished business.

Detective Sean McKinney is the principled protagonist responsible for investigating the new wave of violence that seems to be inexplicably linked to the previously fallen officer. Together with a police psychologist, they dig into the deep and dark corners of the police department's past, attempting to unravel the mystery behind Cordell's return and put an end to the horror he's inflicting. As they come face-to-face with the corruption and the betrayal that sparked Cordell's break from a committed officer to a vengeful specter, they must deal with not only a physical threat but the shadow it casts on the very institution they serve, all while the body count continues to rise.