S18, E2: The sniper plays a macabre game of cat and mouse with the police, while Jack forms a friendship with the teenage son of one of the victims, offering sympathy and support. Thomas tries to ensure the safety of his daughter Rosie and estranged wife Julia amidst growing public fear, while fighting his urge to interfere in their lives. Nikki and Jack look closer at the targets to elucidate the hidden motive of the killer. The investigation is scaled up by DCI Jane De Freitas, but it's Jack's shocking discovery at one of the victims' homes that leads the team to the perpetrator.