Based on real events. The second half of the sixties. Among the radical youth of West Berlin, a Soviet agent with the call sign Zenit is active. Together with the leaders of the anti-American movement, he participates in protests, smashes the den of neo-fascists, sets fire to the office of pro-Western media, develops a plan of terrorist attack during the visit of the US Secretary of State to Germany... The intelligence officer manages to find out that American scientists are conducting secret experiments on students using psychotropic substances. Their action paralyzes the will of a person, allows you to extract any information from him. Our illegal immigrant, secretly captured by Western intelligence services, is being held as a test subject at one of the US military bases. The release of a colleague from the hands of tormentors becomes a matter of honor for Zenit and his comrades…