Recounting the case of police officers David Wombwell, Christopher Head and Geoffrey Fox, who were killed by hardened criminal Harry Roberts and two associates while patrolling an area of west London in August 1966. Dubbed The Shepherd's Bush Murders, the crime shocked the nation.
How wanted murderer Dale Cregan ambushed and killed two female PCs on a routine callout in Manchester in September 2012.
How the stopping of a suspected stolen car led to the murder of PC Ian Broadhurst by fugitive David Bieber, who was on the run from Florida law enforcement.