Detective David Creegan is assigned to the FBI's Organized and Serial Crime Unit – a rapid-response, elite crime investigation squad – upon his return from a year-long psychological leave of absence following an almost-fatal gunshot wound to the head. There, he and his new partner, Detective Susan Branca, find themselves committed to saving lives and solving cases. Creegan, with Branca's assistance, is determined to track down the most heinous offenders operating in the city, despite the fact that he is unable to adhere to common reason or the laws that he has taken an oath to protect.