Moscow, 1959: Katya is young, beautiful - and a spy for the British. When she begins spying on Alexander, an idealistic Communist politician, the last thing she expects is to fall in love with him.

Her choice between love and duty leads to a nail-biting conclusion that Alexander can only unravel decades later in present-day London. His journey back to the snowbound streets of Moscow uncovers a love triangle and betrayals from those he trusted most.