The title of the film relates to what is claimed to be, at the time, an East-West agreement (between NATO and the USSR) established to prevent runaway nuclear proliferation. One of its clauses is known as the Fourth Protocol and is secret: it bans the non-conventional use of a nuclear weapon against any target. At the start of the movie, taking place in 1968, John Preston (Michael Caine), an MI5 officer, establishes that George Berenson, an official in the British government, has been passing on top-secret NATO documents to a foreign power. The film develops from there.
The story involves Soviet agents sent to Britain to cause mayhem; intrigue and infighting within the various agencies and personnel involved on the Soviet side, but also on the British side; and, finally, a plucky, no-nonsense counter-terrorism agent (Michael Caine) who will do what it takes to save the country - and the world. On the Soviet side, an elite intelligence officer is his opponent: a cold-hearted and homicidal Pierce Brosnan, as Major Valeri Alekseyevich Petrofsky (AKA James Edward Ross).
The film is not bad but it is not that great. The suspense is somehow a bit limp. The plot is riddled with implausible twists and turns, and yet bizarrely predictable (it manages to be both, in other words). The characters are cartoonish, to a large extent. It is a B-movie, in the last analysis: it feels as if it was made in the 1970s (the story is supposed to take place in 1968 but it was made in 1987). In fact, it almost feels like a run-of-the-mill TV drama. In conclusion, I would pass on this one, even though it is enjoyable enough to watch and is not boring as such: it simply is not necessary.
This is a trip down memory lane, a British thriller from the 80's that proves to be quite a flashback. Caine plays his usual role of a maverick character, operating on the extremes of his remit to get results. A young Brosnan is a cold, clinical KGB agent following orders without question. Overall the Fourth Protocol is a standard political thriller, typical of the period. Restrained by budget, it lacks many of the huge explosions and effects we have come to expect from thrillers nowadays. The action sequences are particularly cumbersome and a few of the supporting cast are very wooden.