The fourth protocol is a secret addendum to the nuclear non-proliferation agreement signed between the USSR, the USA and Great Britain in July 1968. A top-secret group of powers decides to break it. A Russian special agent is assembling an atomic bomb piece by piece in Great Britain, the explosion of which is intended to upset the balance of power in the world. John Preston tries to prevent the impending disaster in a race against time.
The film adaptation of Frederick Forsyth’s novel of the same name was made by the acclaimed British director John Mackenzie, who signed, for example, the classic gangster film Long Friday (1979). He cast the star Michael Caine in the main role of British agent John Preston, and his Russian counterpart was played by Pierce Brosnan, who was not very well known at the time.