British nuclear scientist buckles under the pressure and issues an ultimatum--Britain must denounce nuclear weapons or he will blow up "the seat of government"--meaning about 12 square miles of London! And he has the suitcase bomb to do it! You can guess the basic part of the ending early on, but it is still a pretty tense climax. This seems to have a cast of thousands and there are some impressive scenes of evacuation and London's empty streets, methodically searched by troops. Good performances all around, including the dog Trixie. ( )