In his first hour back from a six-month leave of absence, Detective Jacob Striker's day quickly turns into a nightmare. He is barely on the scene five minutes at his daughter's high school when he encounters an active shooter situation. Three men wearing hockey masks - Black, White, and Red - have stormed the school with firearms and are killing indiscrimintately. Striker takes immediate action. Within minutes, two of the gunmen are dead and Striker is close to ending the violence. But before Striker can react, the last gun man - Red Mask - escapes. Against the clock, Striker investigates the killings for which there is no known motive and no suspect. Soon his investigation takes him to darker places, and he realizes that everything at Saint Patrick's High is not as it appears. The closer he gets to the truth, the more dangerous his world becomes. Until Striker himself is in the line of fire.