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.
Source : Wikipedia