Knox kicks off a new series featuring dysfunctional Manchester detective, Aiden Watts. Watts is tasked with finding Isabelle, a politicians runaway daughter. She's believed to be in the grasp of Zain Carver, a ruthless drug dealer protected by corrupt officers. Carver deals in local bars and uses beautiful girls, called Sirens, to collect. Watts poses as a dirty cop to get closer to Carver and Isabelle, but as he does he discovers Carver may be less dangerous than what Isabelle left behind.