The horrific murder of two MI5 informants lead the team to discover a leak at a government-run Missing Person's Scheme. The race is on to find the source of the corruption and stop the killings before they escalate. Rachel goes undercover to find further information on the MI5 cover up and learns a British scientist may have been wrongly imprisoned for his part in the bomb plot.

• David Wolstencroft

• Andrew Knott
• Oona Chaplin
• Kenny Doughty