From the start this is a tense film. Nigel Kneale drops you straight into the confusion of a military cordon surrounding the London embassy of the recently independent Republic of Makang. Kneale gives us little explanation, leaving us to piece together what is happening ourselves.
The incessant honking of car horns and chaos outside the embassy - the modern world, where the Prime Minister (Andrews) is trying to get a handle on the situation, makes a startling contrast to the peace and quiet inside the building. In the cellar, a crude thermonuclear device has been constructed and is being used to hold London to ransom by the Ambassador (Maxwell) and President (Wolfe).
Two performances really stand out here. Andrews' gruff and level headed Prime Minister and Maxwell's dignified and decent Ambassador. The confrontation between them brings out powerful performances from both: Andrews tries reason and threats of nuclear retaliation - Maxwell calmly and believably explains his love of his homeland and its people, pillaged of their resources by the British and forced to conform to ways of 'modern' living instead of the old ways which are their own - Andrews realises he cannot win.
The wild card is Wolfe's splendidly unhinged President, who is fuelled less by a love of his people than by a deep hatred of the British. This hatred leads to the film's final sequence, an incredibly tense showdown in the cellar, between the old ways of the Ambassador and the modern world of the President. The film ends as unexplained as it begins, relying on us to read what we will from the expression on the dead Ambassador's face.