Columbine. Dunblane. Virginia Tech. Winnenden. But Saint Patrick's High?

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 scene five minutes at his daughter's high school when he encounters an Active Shooter situation. Three man wearing hockey masks have stormed the school with firearms and are killing indiscriminately. Striker takes immediate action. Within minutes, two of the gunmen are dead and

But the last gunman, Red Mask, does something unexpected. He runs up to his fallen comrade, racks the shotgun, and unloads five rounds into the man, obliterating his face and hands. Before Striker can react, Red Mask flees - and escapes.

Against the clock, Striker investigates the killings for which there is no known motive and no known suspect. Soon his investigation takes him to darker places, and the closer he gets to the truth, the more dangerous his world becomes. Until Striker himself is in the line of fire.