NOW A MAJOR FILM STARRING JUDI DENCH AND SOPHIE COOKSON

Cambridge University in 1937 is awash with ideas and idealists – to unworldly Joan it is dazzling.

After a chance meeting with Russian-born Sonya and Leo, Joan is swept up in the glamour and energy of the duo, and finds herself growing closer and closer to them both.

But allegiance is a slippery thing. Out of university and working in a government ministry with access to top-secret information, Joan finds her loyalty tested as she is faced with the most difficult question of all: what price would you pay to remain true to yourself?