Ver PelisPlus. The story is based on Operation Stone, during which State Security agents deliberately misled citizens of the Czechoslovak Republic who were attempting to leave the country illegally by creating fake borders and fake border patrols and interrogation teams from American, German, and French authorities. During interrogations, State Security officers convinced detainees that they had actually crossed the state border of our republic and obtained information from unsuspecting people, which was then used in criminal proceedings.