Bored with life as a teacher in an Edinburgh girls' school, artist Rosie recognises Alex Kuznetsov from her previous life as a decoder at Bletchley Park. Alex, a war hero and anti-Soviet intelligence officer, is running a Russian language school for National Servicemen to put Britain's best and brightest young men through intensive training as translators and intelligence operators in the event of a third world war. During an ardent courtship, Rosie joins the JSSL as an art teacher, but she soon finds out that there is more to her role as Alex gains her confidence and persuades her to take on a daring undercover espionage mission in a Highland country house. Rosie discovers that the world of spies is full of treachery, manipulation and deceit, and that what started out as a thrilling game can have deadly consequences. Faced with a choice between duty and love, and between stability and adventure, Rosie must decide where her loyalties lie.