A defecting KGB officer reveals details of Operation Glass, a devastating Soviet plan that threatens to change the course of the Cold War.

The team must ensure that Tom Mallory, a Societ agent, is freed from prison in order to use him to get them one step closer to thwarting Operation Glass.

The team are given another name and discover a sleeper agent, a trained spy with connections to the United States military and access to US bases.

The team discover that the KGB are one step ahead of them, so Joe attempts to convince everyone to use Arkady to put a double agent scheme into motion.

The team is reeling after their shocking discoveries but there's a new name to investigate and it's down to Wendy to go in undercover to suss him out. The team hope she's ready for the challenge but when Philip turns out to be a tricky target, will she hold her nerve?

Following a KGB bombing and a confession from a mole, Operation Glass continues towards its ultimate goal, leaving the team rushing piece things together before it's too late.