The episode starts out with the Seaview visiting the icy wastes, which gives them a fine excuse for their classic broaching shot--in color, no less! They are checking out rumors of a new weapon being tested. Twenty-five miles from the test site, not only does the rumor turn out to be true, but the weapon is far more powerful than anyone guessed.
The scene hops to Nelson's office at the Institute. Nelson seems to have run through his supply of secretaries for the moment--having none at all for the previous episode, he now has Stu Riley, of all people, subbing for one. Nelson finds that the super-powerful weapon they witnessed was indeed as small as it had been claimed to be, leading him to conclude that it was a proton bomb. A larger bomb of the same type could be devastating to the world.
Meet Dr. Everett Lang, who, with a couple of colleages, has invented the bomb. Lang had defected from the United
States to some country behind "the bamboo curtain". We're not told precisely what his grievance against the U.S. was, but apparently he has the naive idea (naive being a gross understatement) of forcing the world to disarm its nuclear weapons by threatening it with an even deadlier weapon. The leader of Lang's adopted country shows his opinion of such idealism by having Lang and his associates gunned down in a spray of bullets (and not one drop of blood, fancy that). The guards must have been hideously bad shots using very cheap ammo, because Lang manages to survive the shootout and escape. He gets out a distress call to the U.S, promising to give them something "important"--but only if Seaview is the ship that comes to his rescue. Because of Lang's background, Nelson suspects that the important something is the proton bomb.
Dr. Lang, who seems at first to be quite badly wounded, commences a rapid recovery, quite ably assisting in dispatching two agents who have discovered him. He puts another call through to the U.S, this time admitting that his information deals with the proton bomb, and again demanding the use of Seaview. Nelson agrees. Crane, more pragmatically, refuses to take the Seaview in directly, fearing that the traitorous Lang might simply be trying to draw them into a trap. He proposes going in alone to find Lang, and only then bringing him to a rendezvous with Seaview. This not only gives Crane the chance for some undercover action, but they get to haul out the Flying Sub as well.
Crane starts his search for Lang disguised as a legless beggar, only to be nailed by the police. The two police officers in question turn out to be part of the underground--although it's quite clear that Crane was not aware of this until he was carried into Lang's hideout and one of the officers introduced himself. There's a brief, very nicely played bit here: Lang walks up to Crane, extending his hand--and Crane refuses to take it.
Lang, at this point, seems to have pretty much recovered from whatever wounds he had suffered. Crane, on the other hand, who has been in a cramped, kneeling position for hours, has to work the kinks out of his legs before he can stand, which I thought was a nice touch of realism. A female agent, Su Yin, has made arrangements for them to travel out to a junk, and from there to the Seaview.
The junk is captained by one of the top smugglers of the area. Lang starts to show some of his arrogance at this point, insulted that Su Yin paid so little for his escape. Somewhere along the line, there was a leak, for the authorities get wind of the escape and come after the junk. They attempt to fight back, Su Yin getting killed in the progress, but the police boat is faster and better armed, and ends up blowing the junk out of the water. They neglect, however, to make much of a search for survivors, and Crane and Lang both make it back to the Seaview.
Lang leads the crew to where his new, larger proton bomb has been set in the sea bed. This part raises a few questions. In the first place, the bomb's original position seems to be in a place where, if activated, it would harm Lang's adopted country. You'd think that they would have placed it at a safer distance. Lang warns them that if they bring the submarine closer than 200 feet, it will activate the bomb--then he tells them that if they get too close, it will trigger off missiles. I should think that the bomb going off would do quite enough damage--the missiles would be redundant. You would also think that there would be a patrol in the vicinity to prevent any other submarines from unwittingly straying too close and accidently bombing a good chunk of the planet.
Oh, well. The underwater shots are beautifully done, as usual, even if the bomb does bear a striking resemblance to both the life buoy from "Submarine Sunk Here" and the habitat of "Leviathan". (Nice, thrifty guys, those special effects people.) There's a lot of tension as Lang and Nelson carefully manuver through all the gadgetry designed to keep people away--although the moment where Nelson neatly catches a falling tool passes by so quickly the viewer hardly has time to realize the danger.
Having ensured that no one can set the bomb off by remote control, Lang promptly shows that he has learned nothing from either his own bitter experiences or from Nelson's sharp comments. He's bound and determined to force the world to disarm--or die. His idea seems to be that if the world won't disarm RIGHT NOW, then he will just put it out of its misery. He refuses to concede that the world just might possibly decide to disarm of its own free will.
Lang may be deluding himself that he's acting for mankind's benefit--but just watch how he overreacts to such a minor matter as fetching a chair for him to sit in. The man is already drunk on power--thereby proving Nelson's comment about the danger of having one person in complete control.
Lang's comment about man's destiny being his to shape makes me suspect that he would not have been satisfied with getting the world to disarm--he would have gone on to more and more demands. Nelson convinces the Powers That Be to pretend to go along with Lang's demands while he thinks of a way to deal with the situation. Sharkey darn near blows the whole shooting match when he decides that Lang will never really set off the bomb, and all that's needed is some simple brute force. He manages to talk Riley into going along with this, but Chip Morton catches them just in time. Chip threatens Sharkey with arrest, but under the circumstances, the man really should have been put on report. Sharkey really lucked out here.
Nelson determines that the bomb will not blow up the moment Lang hits the button; it will take time for the detonator to actually reach the explosive. He says it may take minutes, or it may take seconds. Fortunately for all concerned, it does take minutes, because they certainly take their sweet time in dealing with the bomb once Lang activates it. In fact, Nelson's plan does not work, and he must hastily yank out the explosive part of the bomb before shoving the rest of it outside to detonate relatively harmlessly in the water.
Once again, the world can breathe a sigh of relief. Nelson concedes that, while Lang's motives were laudible, his methods were not, the price of peace being, in this case, far too high.