A brilliant detective is forced into early retirement after losing eyesight. Making ends meet by solving cold cases for reward money, he teams up with a rookie lady inspector to solve a case from her personal past.

"5 cops only in Sham Shui Po tonight!" PC46700 said. In the deep of the night, a police officer was dispatched to an old building where he found a Vietnamese drug addict in a partitioned room. His investigation was inexplicably filmed by a would-be documentarian, which led to a conversation with the police constable recollecting his early days and involvement with the Vietnamese refugees more than twenty years ago. An apparently unrelated group of people had this unexpected encounter when the majority of the police force gathered at Mongkok during the Umbrella Movement.