Home alone, Hang Yin Leung hears a knock at the door of her family home – her husband, with whom she runs a takeaway business, is at work. The house is ransacked by six men, but the worse is yet to come as Hang Yin is later hospitalised and admits to the police the nature of the brutal attack.
Eleven days after hearing that first knock on the door, Hang Yin died from the injuries she sustained. The police struggle to piece together a case, but with two weeks having passed they are unable to rely on forensics.
The episode, filmed over the course of 12 months, grants the viewer extraordinary access to the police as they tackle one of “the most difficult homicides” they have ever faced, pouring over CCTV evidence, waiting to uncover a clue or mistake made by one of the murderers.
The episode also focuses on the Leungs, migrants from Hong Kong who travelled to the UK in search of a better life for their son.