Scripted by Frederick Forsyth from his own novel, The Fourth Protocol is a fact-based spy thriller. The titular protocol is a secret agreement between America, Britain and Russia to cease smuggling nuclear weapons into their respective countries. This figures into the schemes of several rogue spies, who hope to destroy NATO by embarking on just such a smuggling endeavor. Russian agent Valeri Petrofsky (Pierce Brosnan) is ordered to stage a nuclear accident in England, then arrange the evidence to point to the Americans. British intelligence agent John Preston (Michael Caine) begins wondering why such nuclear-weapon components like lithium are showing up in the unlikeliest places. Ignored by his superiors, who figure that Preston is merely an old-line anti-Commie paranoic, Preston gathers the clues that will enable him to find out who's behind the potential breaking of The Fourth Protocol.
KGB agent Major Valeri Petrofsky has been reassigned at the request of the KGB Chairman for a secret mission wherein he is sent to England to establish a residence near an American military base and receive various items from couriers from the USSR. John Preston is the top British spy catcher, currently at odds with his superior because he doesn't lick his boots. After he conducts an operation without his superior's permission caused his superior some embarrassment, he is reassigned to the menial task of overseeing airports and ports.