MI5 tolerates Charlie because he's their best field agent. What no one knows is that he is married to Natalia Fedova, a colonel in the FSB, the Russian intelligence successor to the KGB. It's a secret that could land her in front of a firing squad, and him land in jail for life. Worst of all, their daughter would then end up in a Russian state orphanage.

A frantic call from Natalia has brought their secret out, and Charlie must lead a combined MI5/MI6 mission to rescue her. He soon realizes that his higher-ups have other priorities than his family's safety. To keep them safe, Charlie will have to outwit not just the Russians but his own government as well.