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 for couriers from the USSR. John Preston is the top British spy catcher, currently he is at odds with his superior cause, he doesn't lick his boots. After a recent operation caused his superior some embarrassment, he is reassigned to the menial task of overseeing airports and ports. One day one the couriers Petrofsky was expecting had an encounter with customs which left him dead. Preston then went through his things and found that he was carrying a thing that is part of an atomic bomb. Preston then suspects that someone is bringing in parts for an atomic bomb, and after being shut down by his superior, he is given a reprieve by a higher official, and begins trying to find this person. And back in the USSR, Petrofsky's boss is so disgruntled that Petrofsky has been taken from him that he calls his old friend, the Vice-Chairman of the KGB to find out what's going on, cause he believed that the Chairman couldn't be able to do any of these things without his friend's input. But his friend is just as incredulous as he is. So he tries to find out what the Chairman is up to.