It starts out looking like a rather dull, routine day in the submarine service. Then a flicker of irritation, a rather sharp exchange, and then...we're left staring in horror at the abrupt explosion of fury.
Naturally Seaview is called to to investigate what happened to the Angler. (Kind of a dull name for Seaview's sister sub). Divers are sent to retrieve the Control room recordings and the ship's log (and I would love to know just how they managed to heave that safe from one sub to the other). They listen to the final, frenzied moments on board the Angler, which are just as frightful to listen to as they were to watch--you can't blame Crane for snapping off the recording. They hear references to "the island", check it out in the log, and begin backtracking.
Nelson starts to get an inkling of what is going on when they reach the island and find a pair of jungle cats that had apparently killed each other. Finding a cave-like area, they spot clear evidence that the island is inhabited. Seeing a door suddenly open, they accept the implied invitation and walk in...
...and find everything turned askew. The room has been designed as an optical illusion (I've seen pictures of a similar experiment in an old Time-Life book) making the persons inside appear to shift radically in size. General Tau makes his appearance in giant economy size, obviously revelling in the impression he makes. Nelson and Crane are relieved of their weapons, as well as Nelson's watch and Crane's signet ring.
While Richardson and Williams had been affected by the experimental drug by accident, General Tau has decided that he wants a proper experiment done with human subjects. Dr. Shinera sets out to test the level of Nelson and Crane's friendship first, as the experiment would be void if the two men didn't like each other to begin with.
Chip Morton, in the meantime, has come to the island as per orders, only to be ordered off by General Tau. Chip does not have the authority (or, at the moment, the firepower) to press the issue, and he and his men beat a reluctant retreat. General Tau hints that the currents around the island are treacherous to small craft, and the Seaview locates the minisub some two thousand feet down. On sending a deep sea diver to investigate, they find Nelson's watch and Crane's ring. (I would like to know just who provided the badly battered bodies the diver found in the sub, because it doesn't seem likely that he would be taken in by dummies.)
Tau and Shinera contrast strongly with each other. Tau is aggressive and impatient, wanting to quickly prove the merits of the drug so that it can be used as a weapon. Shinera, on the other hand, is ice cold, purely interested in the scientific aspects, and regarding Nelson and Crane merely as reasonably intelligent lab rats. It's rather creepy to watch him anticipating their reactions, step by step. Although I do think that Crane, seeing a televised view of Nelson in comfortable surroundings, should have realized that someone was trying to mess with his mind.
Having been released--and conveniently finding weapons to hand--Nelson and Crane have a brief moment of confrontation, but their contrived hostility quickly fades--thereby proving the reality of their friendship to Dr. Shinera. Nelson and Crane mull over what has happened to them so far, and Nelson begins to draw conclusions. Unfortunately, before he works everything out, Crane has ingested some of the drug in the form of berries. At this point, knowing Crane might suddenly go into a killing rage, Nelson should have asked him to hand over his gun--or Crane should have voluntarily given it to him.
The psychological cat-and mousing is abruptly replaced by pure action, as Crane is overcome by the drug. (I wonder how David Hedison liked charging around the set, screaming like a madman?) Nelson just manages to keep himself in one piece and a step or two in front of Crane. You really have to admire his presence of mind. With the threat of imminent death at the hands of his friend, Nelson takes time to remove the hose that provides clean water and tosses it into a contaminated pool.
Chip Morton and Co. have returned to the island, although we're never informed why. After all, they presumably thought that Nelson and Crane were dead. Were they following orders from Comsubpac? Were they attempting to finish the investigation started by Nelson and Crane? Or did they just have vengeance in mind? Whatever the case, they made it to shore with no one noticing them. (Under the circumstances, it's possible that the General's men avoid going outside unless they're specifically ordered to.)
General Tau, still impatient, and unable to find his subjects on camera, rushes out to find them, and does so at about the time that Crane finds Nelson. Nelson manages to get hold of the gun and deals with Tau. Crane gives a fine demonstration of the meaning of the term, "blind fury"--he keeps swinging at the trapped Nelson with a heavy stick and misses every time. He swings with such force, in fact, that he loses his balance. Chip and Co. turn up in time to haul Crane away from Nelson, and head back to the Seaview--with Crane presumably struggling and screaming every step of the way, unless they bopped him over the head.
They never did consider the possibility that the drug might have a permanent effect. Fortunately it did wear off--although we don't know how long it took. Crane's resentment at their treatment is mollified by Nelson's very casual confession of switching the island's clean water supply for drugged water. (Considering the amount of tea and boiled noodles Dr. Shinera consumes, he'll probably be the first to go.)