Joan Stanley (Judi Dench) is enjoying a quiet retirement until she’s arrested by MI5 for multiple breaches of the Official Secrets Act. As it turns out, beneath Joan’s calm exterior there’s a dark and shady past. A former spy for the KGB, she has gone undetected for more than half a century – until now.

At Cambridge University, in the 1930s, the young Joan (Sophie Cookson) is a seemingly unassuming physics student. But her whole life changes when she falls in love with suave Russian saboteur Leo (Tom Hughes) and gets pulled into the politics of the communist Soviet Union.

Fast forward to the post-war period, where Joan is working at a secret nuclear research facility, and she’s forced to decide whether to slip the secrets of the nuclear weapons that she’s been working on over to Russia.

As UK intelligence struggles to work out how the USSR is keeping up with its development of the atomic bomb, Joan quietly continues her double life in the hope that she can preserve peace for the UK and her loved ones.

Judi Dench (Murder on the Orient Express) stars in this English drama about one woman’s sacrifice, based on the true story of the spy Melita Norwood. Featuring Sophie Cookson (Kingsman: The Golden Circle), Tom Hughes (Victoria) and Stephen Campbell Moore (Goodbye Christopher Robin), Red Joan is a story about duty, love and the consequences of the actions that might have saved the world.