Roxton is looking for the materials for a crossbow to bag a T-Rex, but when one actually interupts him in his labors, he runs in the direction opposite his fellow travelers to keep them safe. He winds up falling into a hole that suddenly opens up. When the rest of the group search for him, they also fall into the hole, which turns out to be a whirlpool. It sucks them all under the water, and they emerge in a lake. They quickly find out that in this part of the plateau, the dominant species are lizard-like men, descendents of dinosaurs, and the humans are subservient to them. There is an ancient Roman structure to this civilization, including gladiator-type battles. While Marguerite and Veronica are forced to change into silky gowns for the entertainment of Tribune, the lizard-people's leader, Roxton is chosen to fight another human prisoner. The slaves and travelers rebel, and overthrow the lizard-men's intolerable rule, but not without loss ~ Roxton's opponent's sister ~ a rebel leade

Veronica and Summerlee are out gathering fruit and floral specimens when they are attacked by a huge bee, one the size of a man. Summerlee is stung, and it leaves him near death. The only cure is the nectar in the heart of the hive. Veronica, Malone and Roxton travel to the hive, leaving Challenger and Marguerite behind at the treehouse to care for Summerlee. Summerlee is delirious with fever, and imagines Marguerite is his long-dead wife. She plays along, to sooth him. In the meantime, Veronica, Malone and Roxton do make it to the hive, work their way deep into it, gather nectar, and head back quickly to the treehouse, just in time to save Summerlee's life.

Challenger, Malone and Veronica are searching for sulfur, in order to make more gunpowder, when they walk into a burial ground. They are attacked by warriors in black and white paint who capture Challenger. That night the group sneaks into the warriors' village...to find Challenger sitting quietly and drinking tea with a beautiful blonde woman named Cassandra. She and her husband had been part of an early expedition, also stranded and found by the warriors tribe twelve years ago; they were soon made king and queen there. She tells our group that going onto the burial grounds was considered taboo, and for this Challenger would have to remain captive for life. The only way they can save him is by going to the Cave of Fear and retrieving her husband's bones for burial. They set off, but soon discover why the cave is avoided ~ it's walls are covered in a hallucinogenic fungus, wtih a really nasty additional effect. It drives those affected to suicide - which Cassandra apparently knew when

In this episode, Challenger, Summerlee and Veronica save a little girl from drowning and Summerlee has to give her mouth to mouth resuscitation. Tolmac, of the Christec people, brands Summerlee a witch for bringing the girl ""back to life."" The Christecs have mingled the Catholic and Aztec religions, with a touch of Conquistador Inquisition, to form their theocracy. Veronica gets away to summon help from the others, but Challenger has to act as Summerlee's lawyer ~ if found guilty, both men will be burned at the stake.

While wandering the plateau, Roxton is attacked by a young man, who bites him during the struggle. Roxton's infected with a disease whose symtoms are slightly bizarre ~ intense craving for blood, pain when exposed to sunlight, a powerful feeling of kinship with nature and ""creatures of the night"" - he is as a vampire. He runs mad and into the gothic mansion of Calista, a beautiful woman with the same disease. Back at the treehouse, a young native man, Niko, comes forward, declaring his love for Veronica. He and Malone argue and decide to fight to the death for her; she is not pleased! Outside the treehouse, Malone and Niko do start to fight, but quickly stop when Veronica tells them she will kill herself to stop them, and has a knife at her stomach to prove it. Niko leaves, but tells her he'll never forget her. Veronica remains mad at Malone for a while for trying to fight her battles. In the meantime, Marguerite and Challenger discover all about the disease, and search for Roxton, not

Roxton, Marguerite and Malone are mapping a series of caves, trying to find one that leads off the plateau without much luck. Marguerite, all the while, has been gathering gleaming gemstones in her backpack. At least she will not go back empty handed. A fog begins to fill the air around them...dense...deep fog. From out of the mist forms take shape: cloaked figures and eerie rock formations, encircling a stone slab. They find themselves surrounded by Druid-like figures who swarm over Marguerite. Roxton tries desperately to protect her, but she is torn from his grasp. The two men are restrained and Marguerite is carried away and deposited on the stone slab. It turns out that Marguerite figures in an ancient prophecy and that her fate has finally caught up with her, here. What it means, she must discover for herself, but it involves retrieving a sacred jemstone. She, along with Roxton and Malone, must go through several obstacles like headhunters and a leap of faith to accomplish Marguer

The aged guide who brought Veronica's parents to the Lost World dies in Challenger and Veronica's arms, humming ""Ode to Joy,"" leading the explorers to seek out a hidden paradise, where Veronica suspects her parents might be.