• Season 1 Episodes
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• Season 3 Episodes
• Season 4 Episodes
• Plot Synopses

Guest Cast:

Jason Kemp..................Nick Adams 
Carol Denning...............Yvonne Craig 
Dr. Denning.................Les Tremayne 
Native Girl.................Vitina Marcus 
Ziegler.....................Robert Cornthwaite 
Naval Doctor................Robert Patten 
Crewman.....................Mark Slade

As a man of science, doctor, you should be as careful as I am about using the word "impossible."--Harriman Nelson

On a tropical beach, a man runs from a dinosaur. He takes out a bag and inflates it, then enters the water. He swims downward, breathing from the bag.

A woman is in a darkroom developing pictures. Crane knocks on her door and calls her name, "Carol." She is pleased and surprised to see him, and invites him into the darkroom while she finishes her work; she asks what he's doing there, and he says Nelson sent him to get her--Jason Kemp has been found, alive. She asks about her father and two other men, but only Kemp was found. It was a miracle; after nine months lost in the Antarctic, Kemp was found. He is in the United States now, at Bethesda Naval Hospital. Carol says she'll be ready to go in five minutes.

At the hospital, Nelson, Crane and Carol are at Kemp's bedside. Kemp takes Carol's hand and asks if she is still his girl; she says of course she is. He remembers nothing about the past nine months. Carol, who was with the party just before they were lost, describes what she remembers; they were on an icebreaker, and the party--Kemp and Dr. Denning (Carol's father) from the Denning Institute, and two men from the Nelson Institute--went into the diving bell. The cable broke, and they searched for days until the ice closed in, but found nothing. Kemp remembers nothing after the bell went down. The doctor says that it's temporary amnesia, not uncommon after a traumatic event--even the tape Kemp made after being rescued was no help in determining what that event was, mentioning a tropical oasis and dinosaurs--obviously Kemp must have been delusional. Nelson and the doctor go to the doctor's office and listen to the tape; Nelson wonders if it could be true--after all, how long could Kemp have survived in the Antarctic otherwise? The doctor is skeptical, but Nelson says that it is possible, citing several examples of warm areas in cold regions. The doctor then shows Nelson the bag Kemp had with him when he was rescued; it's animal tissue but they have been unable to identify it. Nelson goes to the International Science Academy to consult with Dr. Ziegler, the paleontologist. Ziegler identifies the tissue as being from the esophagus of a dinosaur, and says it must be 150 million years old. Nelson asks him to test in on his atomic clock, and Ziegler can't believe the results--less than a year ago, the source of the sample was still alive.

Carol and Kemp board the Seaview; when he learned they wouldn't postpone the expedition, Kemp insisted on going along. Nelson asks about suitable accommodations for Carol aboard the ship, and Crane says he is letting her use his cabin. She's escorted there, and Kemp follows, thanking Crane for taking care of his girl while he was missing. Nelson says to get underway immediately.

As they approach the site of the bell's disappearance, the Seaview's sensors note underwater peaks where they shouldn't be, and the ship collides with one. Crane says they were lucky the damage was minimal--there's a 2 degree error in the inertial navigator. Without that, they can't continue the expedition. Crane suggests returning to the Falklands for repairs. Carol becomes agitated--they can't delay! Crane says he can't risk the lives of the crew; Carol looks to Kemp for support but he agrees with Crane. He says also that if he was able to survive for nine months, her father and the others should be able to last another week. Nelson, however, says he may be able to repair the inertial navigator, since he designed it. He can, and the expedition continues.

When they reach the point where the bell disappeared, they find the water is 59 degrees--and at 100 fathoms it warms to 70 degrees. Kemp says the readings are the same as those of the original expedition. Nelson says he thought Kemp lost his memory; Kemp replies that that happened after the dive. Crane orders the diving bell readied; Kemp asks if they have to use the bell--why not take the Seaview down? Nelson replies that they don't know how deep they will have to go, and the Seaview can't go below 4000 feet. Nelson, Crane, Kemp and Carol enter the bell and it is lowered. As they reach 3500 feet, Kemp remembers that the current hit when they reached 4000 feet. He is obviously terrified, and when the current hits them--sometime after they reach 4000 feet--he panics. Nelson orders the bell pulled back to the Seaview but the cable breaks and the bell is washed away--and up into a tropical cove. They exit the bell and collapse on the beach, not far from a large dinosaur footprint.

The party prepares to search the area. Nelson believes the climate to be caused by constant volcanic activity, and the thermal current which swept them in to have done the same to Denning's party. He is amazed by the prehistoric fauna. Carol says the place is so peaceful and warm, her father must be alive--then calls for Kemp, having found the footprint. Nelson identifies the dinosaur it came from--the same kind as supplied the tissue for Kemp's breathing device. Crane and Carol go search for more tracks, while Nelson and Kemp do the same, circling the water hole. Crand and Carol find another print; Crane comments on the strange vegetation, and Carol goes to photograph some interesting plants. She calls out to Crane--he comes and sees what she has seen--a dinosaur. He grabs her and they run. He shoots at the creature but with no effect. Eventually they find themselves on a ledge, with the dinosaur above. Another dinosaur appears and battles the first, while they huddle on the ledge below. Finally both creatures, fighting, roll off the cliff--Crane and Carol are safe. Just then, Nelson and Kemp arrive. They have found a campsite and hoe to find more information there. Kemp starts to take Carol's arm to help her off the ledge, but she refuses, saying she is all right.

The party goes through thick brush; Crane stops--he thinks he saw something, something human. Nelson tells him to go ahead and look, but not to go too far--the party would wait in a clearing up ahead. Crane sees and follows a beautiful native woman into a cave; she sees a giant spider, screams, but passes by it safely. Crane enters the same cave, is startled by the spider, but kills it with one shot and continues after the woman. He catches her, grabs her, and drags her, struggling, back to the others. In the clearing, Kemp sees a pocket watch and quickly hides it under a rock. Crane arrives with the woman; Nelson says she looks South American, and guesses that her people may have been swept here by a storm centuries ago. The woman sees Kemp and calls out to him. Just then, the party is attacked--they look up to find themselves surrounded by native warriors, who bring them to a primitive prison, putting bars against the door to hold it closed. In their cell, Nelson asks Kemp if the sacrificial altar they passed on the way is meant for them. Kemp says it's for a ceremony to their fire god, taking place at high noon on the longest day of the year. That's less than half an hour away, says Crane. Nelson says that Kemp kept trying to delay them--even attempting to sabotage the Seaview. He knew that if they returned after the longest day of the year, Dr. Denning and the others would be dead--what did they know about Kemp? Suddenly, Denning steps out from a door in the cell. Carol runs to him. Denning had wondered if Kemp had gotten away--the other two men weren't as lucky. Denning says there was a girl who had fallen in love with Kemp, and he used her to escape--leading the other two men into a trap and getting away. Crane says it was no wonder Kemp wanted to stall them.

The native woman brings food to the door and asks for Kemp. Nelson tells him not to let her leave; if she will remove the bars from the door, they can handle the guard. He tries, but the guard grabs the woman and pulls her away. Nelson tells Kemp to stay near the gate and keep the woman nearby. He opens the heel of his shoe where he has concealed a small blowgun with paralyzing darts which will immobilize a man for thirty seconds. As Nelson assembles the blowgun, Crane shakes the door and shouts at the guard, who comes over and pokes his spear at them. Nelson shoots him with a dart; he staggers back and passes out--but the woman won't come near the door. Nelson tells Crane to come away from the door--Kemp will have a better chance of convincing her if he's alone with her. She removes the bars just in time. Crane knocks out the guard and they take some torches and make their escape. There are two ways out, one which will take them back to the pool, and the other--more dangerous--which will take them out of the tropical oasis. They opt for the pool, but unfortunately that way is blocked by natives and they must take the other path. They move through a cave, carefully along a ledge, above a river of molten lava. The natives follow; Nelson sets fire to a wooden footbridge they have passed, and the natives can go no further. As they exit that part of the cave, the woman returns the way she came. Suddenly, a dinosaur rises out of the water, blocking their way. Nelson looks up--there is a log holding a dam together--if they can break that dam, lava will pour over the creature. Crane starts toward the log but the dinosaur sees him; he asks someone to distract the beast, which Kemp does by getting himself eaten. Crane uses the log to break the dam and the dinosaur is drowned in lava.

As they continue through the caves, Nelson says they had better hurry, because once the lave hits the ice the entire island will explode. They reach the edge, covered in snow and ice. The Seaview is there, waiting to rescue them. On board the ship, they watch the island explode. The prehistoric oasis is gone forever, and--says Denning--they have nothing to show for it. Nelson says he's wrong--they have their lives.