The team is reeling from the shocking discovery of a mole among them, and as the Soviet plot continues unabated, it is up to Wendy to give the team the break they need. Meanwhile, when Sarah finds herself in danger, Alan is forced to make a decision that can make or break their relationship. Joe has trouble of his own when leaked information threatens the investigation and the lives of the team.

The team is reeling from a KGB bombing and the mole’s confession, but with Operation Glass hurtling towards a shocking climax, MI5 is running out of time to piece the puzzle together and avert disaster. Bobby and Wendy make a crucial discovery which could have implications at the highest levels of government.