Britain's MI5 tolerates Charlie Muffin because he's their best field agent. What none of his colleagues knows, though, 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 in jail for life. Worst of all, their daughter would then end up in a Russian state orphanage. But a frantic call from Natalia has brought their secret...