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

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

Marguerite is the future Queen of Camelot as far as a boy King is concerned, but the explorers and Marguerite, as well as the King's crafty advisor don't agree.

After days of searching the mountains for a pass off the plateau, Roxton and Marguerite are camped for the night when they are taken by surprise by Norse warriors. Roxton is run through with a sword by the leader, Ursula. As he sinks to his knees, Marguerite is hauled off by the raiders. Near death, Roxton is visited by a mystical young boy named Osric, who offers a deal. Osric will restore Roxton's life so he can save Marguerite. However, there is a catch. Roxton agrees to the deal and Marguerite is saved. It turns out that Osric is the soul of evil who has been imprisoned on the Lost World. He reappears and gleefully informs Roxton that he must murder Bergen, an old man with a long-standing hold over the boys' manipulative intentions. Roxton refuses to kill the old man, but Osric has many deadly ways to get what he wants. Meanwhile, Malone and Veronica must defend their Treehouse from a band of cutthroats who will stop at nothing to take it from them.

The explorers are caught in the middle of a war between Tribue, with gunpowder in toe, and Drakul and his barbaric raiders. One of them will be lost, possibly forever, when this battle reaches its cliffhanger!