It is based on the true story of the Czechoslovak communist Artur London, a defendant in the Slánský trial.

The film is about Anton Ludvik, alias Gerard, vice-minister of Foreign Affairs of Czechoslovakia. He realizes he is being watched and followed. One day, he is arrested and put into jail by an organisation that declares itself "above the ruling party" and put in solitary confinement for months without being told the reason why. Through brainwashing techniques, including sleep deprivation, being forced to walk back and forth all the time, and drugs, he is slowly pressured into confessing imaginary crimes and treason and to repeat this confession in a public court. Years later, he meets his now demoted tormentor, who tries to downplay his role at that time.

Yves Montand lost more than 15 kilos to play his role. Shaken by the 1956 events in Hungary the film was in part Montand settling a score with totalitarian communism and he said: " There was in what I inflicted upon myself [for this role] something of an act of expiation."