London Kills

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 victims housemates, who seem to be hiding something.

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.

The team looks into the murder of a Portuguese au pair.

A father and son are shot in broad daylight.

Adrian shares the name of someone who knows where Sarah is.