In exchange for turning a blind eye, Adrian gives Rob the name of someone who knows where Sarah is, but that person turns up dead. Now believing that Sarah may still be alive, David and his team race to her find her.

When a father and son are shot execution-style in broad daylight, the detectives immediately suspect a gangland hit and worry the violence could escalate. David sees an opportunity to finally apprehend crime kingpin Adrian Cook.

While the team looks into the murder of a Portuguese au pair who was recently fired from her job, Vivienne and Rob start investigating David on the sly, but he remains a step ahead of them.

When an eight-year-old boy finds his grandfather dead in a pub basement, he tells Rob that he was hit by a man with a baseball bat, but Vivienne doubts his story. Later, Vivienne pressures Rob to report that he covered for David on the night of Sarah's disappearance.

Construction workers find the remains of a young man who appears to have been strangled to death more than a year ago, but when his sister is notified, she claims he's been sending her postcards all the while. The detectives suspect the involvement of the victim's housemates, who seem to be hiding something.