It starts out up in the air, rather than down in the depths. We're never told why Nelson is on his way to Washington--the implication is that it's a pretty routine commute. Basehart's reaction as his seatmate strikes up a conversation is excellent--he's clearly annoyed at being interrupted by idle chitchat, but makes an attempt to be courteous. They're both interrupted by the stewardess, who insists that Nelson take his dinner tray despite the fact that he doesn't want it. Maybe she has a quota of trays to hand out, but that seemed rather rude to me. Nelson concedes that he could drink some coffee. His seatmate gets him to look out the window, and quickly exchanges Nelson's sugar packet for a different one. (So now we know that Nelson takes sugar in his coffee.) Nelson is sound asleep by the time the stewardess returns to collect the trays. Nelson's seatmate nods to another man and they both get up. Coming to the front of the cabin, the seatmate pulls a gun, quickly assuring the passengers that this is not a robbery. Pulling parachutes from their on-board luggage, they rig the unconcious Nelson up, and all three exit the plane.
There's a brief jump to the Seaview, with Crane reporting the situation to Chip Morton, and continuing on to Norfolk pending further orders. The scene then moves to what looks like an island penal colony. Inside an office, we see a film clip running of Hitler making a speech and a man in German uniform watching intently (and the entire viewing audience thinks "Ah! Nazis!") Nelson is on a nearby couch, just starting to stir. Hitler ranting; what a lovely sight and sound to wake up to.) The officer turns off the film and assists Nelson. Nelson recognizes the man as Colonel Alfred Schroeder. Schroeder has promoted himself; I couldn't understand quite what he called himself, other than to note that the word ended with "fuhrer". He then introduces his aide, Deiner--Nelson's seatmate. Nelson has been unconcious for two days while they transported him to Schroeder's hideaway. Schroeder personally escorts Nelson outside--warning him that there are many guards. Schroeder has spent the past thirty years hiding from the free world, but working to obey Hitler's order to build a fourth Reich. He doesn't mention just how many of those years have been spent on this island, gathering troops, supplies--and scientists. He claims that, as the future lies in the oceans, he captured Nelson as the foremost marine scientist in the world. He is confident that Nelson will join his team. Nelson is equally confident that he will not. Nelson is led to a room, with a shabby, unkempt assortment of men. Nelson's shock grows as he meets and recognizes the men: Dr. Gustav Reinhardt, the world's foremost psychologist, supposedly dead three years ago in a plane crash. You can see Nelson's face tighten up as he realizes that a planeload of people were murdered for Schroeder to obtain this one man. Anton Miklos, nuclear scientist, whose Oxford lectures had been attended by Nelson. Benjamin Brewster, a top authority in electronics, who had "died" in a skiing accident. Rounding out the group, Tomas Brandi, three time Olympic decathlon champion and considered the world's greatest athlete. Apparently these men are not only supposed to contribute their intellect to Schroeder's cause, but their genes as well.
Another quick Seaview shot has Crane pacing restlessly around. No news. Nelson has been missing for two weeks. On the island, Nelson works to rally the downtrodden prisoners. Schroeder interrupts, cheerfully asking Nelson if he's made his plans to escape yet, and offering suggestions--he wants Nelson to try, and get it out of his system. Nelson takes note of his conceit. The others comment on the Prussion military mind. Reinhardt thinks that Schroeder is close to setting his plans in motion, leading Nelson to wonder what happened recently to speed matters up. They think that Nelson himself was the catalyst. Brewster, who has been there for six years, points out that even if they suceeded in killing Schroeder, another of his men would step into the position. It's the whole idea of the fourth Reich that must be destroyed. Miklos had determined their location by the sun and the stars--they are thousands of miles from the shipping lanes. Nelson sets about bringing the outside world in. That night, Tomas avoids the guards and searchlights and obtains some of the barbed wire from the fence. Inside prisoner's quarters, the others are busily engaged in putting a gadget together to send short-wave signals. They hide everything as they hear someone approach, but it's only Tomas--his hands rather torn from the wire. Brewster puts the finishing touches to their gadget, with Nelson contributing a nail to use as a sending key. As they connect it, it gives out the classic radio whine. Nelson settles down to tapping a succinct message.
On the Seaview, Sparks is at his station, warning Crane that the idea that shortwave can travel around the world is only a theory. Crane tells him to monitor various bands. Back in the room, it's nearly dawn--and Nelson is still patiently tapping. On the Seaview, Sparks suddenly picks up something, and urgently calls Crane. (Crane and Sparks have also presumably been up all night.) It sounds like Seaview code, which Sparks quickly translates. Getting a fix on the signal, they find that it's not too far away. Seaview gets underway, and Crane, relieved at finally hearing from his friend, makes the mistake of sending back a reply.
The reply is picked up by Schroeder, who has been waiting for it. (Come to think of it, if the messages were sent in code, how did Schroeder figure out what they were saying?) Nelson is brought to Schroeder's office. Schroeder compliments him--he had allowed three days for Nelson to build a shortwave, and Nelson did it in one. (This makes things rather confusing. Schroder implies that it's been one day since Nelson was put in with the other prisoners, following two days' travel, which would make three days and the beginning of a fourth--but Crane had stated that Nelson's been missing two weeks, leaving ten days unaccounted for.) Nelson, realizing that he's been performing to Schroeder's specifications, keeps himself calm. It's clear now that Schroeder has no real interest in adding Nelson to his stable of scientists--Nelson was merely the pawn used to get at the Seaview. Schroeder hands him the translation of Crane's message. Carl Deiner seems to be a trifle paranoid--Nelson, unarmed, looks as though he's just balling up the message and preparing to throw it in a fit of frustration--but Deiner pulls his gun as though that crumpled bit of paper could be a weapon. Schroeder is pleased to reveal the details of his plan to Nelson--once the Seaview is captured, it will be brought to a central spot in the ocean to fire two missiles simultaneously at Washington and Moscow, thereby setting off a nuclear war. (The James Bond film "The Spy Who Loved Me" had a similar plot twist, only they used two submarines. Seaview, being a superior sub, could do it all by herself.) Schroeder will then build his fourth Reich from the ashes--literally. He seems totally oblivious to the hideous devastation that will result, which will harm his own nation as well.
Returning Nelson to the prisoner's building, Deiner demands the shortwave radio, and Nelson exasperatedly admits that they already know about it, which naturally leads Brewster to think that Nelson betrayed them. Nelson is also on edge, and responds angrily. Reinhardt points out that this reaction is just what Schroeder wants, and the men reconcile. Fearing that the room is bugged, Nelson leads them outside to report on Schroeder's plans. On the Seaview, they're charging full steam ahead, to the detriment of the engines. (Still haven't gone back to using those Strontium 90 pellets.) It doesn't seem to occur to Crane that he's not going to be able to rescue Nelson if he disables his ship. On the island, by the shower and laundry area, Nelson has reported to the others, who come to agree that, in spite of the obstacles, Schroeder must be stopped. Nelson asks Reinhardt for his views. Reinhardt thinks that Schroeder would believe that--having destroyed the radio (and their hopes) that the men would fight amongst themselves (which they did), and then, change direction. Something bold and foolhardy. So, therefore, they must do so--as a diversion to their real plan. Nelson asks how the Seaview could be trapped, and learns that a channel had been cleared out some two years previously, and four months ago, special wiring had been installed. Someone must go and investigate. Miklos tells Nelson of another man (another scientist?) who had been tortured and killed for going past the fence. Tomas volunteers to go anyway--he knows of a blind spot where he can get by.
Having slipped out again, Tomas knocks out a guard and tosses him onto the fence--which promptly sets off alarms. He grabs the guard's gun and shoots at the watchtower before crawling under the fence--to meet Schroder and Deiner. This was an incredibly stupid move--the idea was to slip out quietly and slip back in again. Nelson and the others must be aware that all heck is breaking loose outside, and the idea of Tomas getting back with none of the guards checking on them is ludicrous. Tomas reports back--with no one questioning how he managed it--and they determine that the special wiring in the channel must be connected to the room with Schroeder's radio and other equipment. Nelson asks about anything "strange" being brought in lately, and learns that nets had been shipped in. Steel nets--submarine nets. They're going to have to destroy Schroeder's control room. Miklos, the nuclear expert, gives advice on homemade bombs--they'll need an outer shell, an electrical charge for a detonater, and an explosive--ammonium or sodium nitrate will do nicely.
Seaview arrives, and pauses half a mile offshore to reconnoiter. Schroeder, who has been one step ahead of everyone the entire episode, anticipates that Crane will send out divers, learn the lagoon is too heavily fortified, and go to the only other approach--the southern channel. Crane, of course, does so. (Thriftily, they avoid the expense of a diving shot, merely showing Chip in his diving gear, dripping wet.) Crane also, as Schroder forecast, completely neglects to send divers to check out the channel as well, instead moving straight in. (Crane, all in all, does not make a good showing in this episode.)
Nelson's group has completed a set of bombs, using hardened mud for the outer shells. Nelson slips out to a shed near the shower to make some additional adjustments to his bomb. He then comes back to the room. He and Tomas will launch the attack on the control room, after the others set up a diversion. Schroder and Deiner (as is their habit) casually stroll up to them. Nelson throws a bomb and starts to run--but the bomb does not go off. Schroeder knew that Tomas had sabotaged them. Schroder casually states, right in front of Tomas, that Tomas' lack of intellect had made him easy to persuade. Tomas doesn't react to this comment on his intelligence, which only confirms it. Nelson punches Tomas. Clearly it would not be a good idea to send Tomas back with the other prisoners, so Schroder graciously permits him to join them in the control room to witness Seaview's capture. Seaview comes in closer. Nelson and the others wait outside of their building (which indicates Schroder's perfect confidence that they can do no harm.) The others are in despair, but Nelson merely waits. His timing is a little off, but the bomb that Tomas had carried with him explodes pretty much on schedule. Schroeder might have been a step ahead, but Nelson sidestepped and got ahead of him anyway.
On the Seaview, with the other scientists being checked out in Sickbay, Nelson explains to Crane how he knew Tomas was the traitor--he checked the fencing and knew that there was no "blind spot". Knowing that Tomas would sabotage the bombs, he repaired his--and added a timing device using his watch. (And if you watched closely when he returned to the room, you could see Nelson very casually slide that particular bomb over to Tomas.) Crane and Nelson are left shaking their head's over Schroeder's mad dream.
Quite a decent outing--but I wish that the plot had not hinged on Crane's mistakes. Schroeder could have picked up the outgoing radio signals, and then, with his equipment, have learned of the approach of the Seaview without Crane broadcasting that he was on his way. And if Crane had slowed down to investigate the channel, it would not have detracted from Nelson and the others' heroic efforts--and Schroeder might have had other tricks up his sleeve to entrap the Seaview.