There's no escape for the Challenger Expedition when Captain Askwith's mysterious airship explodes in a fiery crash. But moments later, when Challenger, Roxton, and Marguerite appear on a British air station in 1915 -- on the same day the airship was launched on its final mission -- they realize they truly have taken the place of the captain's original crew. After two years of struggling to escape the Plateau, Challenger and his friends must now fight to return to it by once again taking flight on the doomed dirigible

While searching for the missing Malone, Marguerite is saved from a cannibal attack by a dashing trio of bandits. Their leader, the elegant Francois Locke, invites her to join his band of thieves. Marguerite declines his offer, only to be presented with proof that Locke can give her what she desires most - a way off the Plateau

While exploring a mysterious dinosaur bone yard, Roxton is attacked by a charging Ttriceratops and kills it, not out of necessity but in anger. However, the bone yard is actually a sacred animal burial ground, protected by a beautiful, half-human, half-dinosaur guardian named Oseena. To punish Roxton for his crime, Oseena curses him to become the prey in a hunt that will end only with his death

An unsettling dream and a ghostly encounter convince Veronica that Malone is trapped in the spirit realm and needs her help to escape. At the same time, Assai and Challenger investigate a mysterious symbol burned into a field of grass, which Assai identifies as the mark of Saros, a bloodthirsty warlord who was overthrown by the Zanga and died swearing to return from the grave to wreak vengeance on the living. Back at the treehouse, Marguerite and Veronica use a Ouija board to contact Malone, which results in a frightening display of poltergeist-like activity, and a brief, but terrifying manifestation of Saros

When Malone finds a knife, he is transported back to the East End of London in 1888, the scene of Jack the Ripper's brutal murders. In the nightmare of his visions, Malone sees his friends playing key roles in the crimes, both as conspirators and victims. Meanwhile, Veronica is approached by a famous British doctor, who enlists her to help find his missing knife

Challenger, Malone and Veronica are exploring ruins on a riverbank, when a man stumbles out of the jungle in a hail of deadly arrows. Malone drags the wounded man to safety, who dies in their arms issuing a cryptic message to find a man named Pierson Rice. Challenger recognizes the name as that of a vain glorious hunter whom Roxton once held in high regard

When Roxton happens upon a hangman's noose dangling from a lonely tree in the jungle, he's suddenly transported back to the American West where he finds himself at the end of the rope. Facing him is Challenger, but in this world he's known as Sheriff Jack Challenger, a cruel lawman who neither recognizes Roxton nor listens to his plea of innocence. Saved by a rancher's widow, Roxton begins a strange journey to clear his name and find his way back to the Lost World

Challenger develops a new way to create lift in the balloon. All go along for a test flight, but the balloon is drawn into violent turbulence then crash-lands inside the vast caldera of an extinct volcano where our heroes find themselves trapped in a world beneath the earth's surface. With the balloon damaged and the supply of iron lost, our heroes can only survive for a matter of days in this hot and hostile environment

When a powerful witch named Dame Alice feels threatened by Challenger's science, she calls upon her two beautiful acolytes to help undo his power. In order to earn full witchhood, the two must lure Challenger's ""guards"" - Roxton and Malone - to the witch's castle while she goes head to head with the ""wizard"" - Challenger - herself. While the two young witches distract Roxton and Malone, Dame Alice visits the Treehouse for a visit

When Keeran Raiders attack, a deadly poison dart forces Malone to relive a long-suppressed memory-his baptism of fire as a battlefield correspondent in World War I. Caught up in this nightmarish hallucination, Malone is once again an untried reporter cut off from Allied lines when an enemy advance pushes deep into No Man's Land. When the three battle-weary British soldiers who've been assigned to escort him are picked off by enemy action, the young reporter who's never fired a gun must take up arms to save his own life and the life of a wounded sergeant

When a blindingly bright meteor strikes the Plateau, Challenger, Roxton, and Marguerite set out to investigate the impact site. But the closer they get, the colder the temperature becomes. As the explorers turn back, they discover what appears to be a victim of the intense cold - a beautiful, blue-skinned woman, unconscious and nearly frozen

Ambushed in the jungle, Roxton narrowly escapes with his life only to learn that he has apparently cheated death once too often. The Grim Reaper, in the guise of a dark seductress - is determined to add his soul to her collection. Transported to her domain - a bleak and desolate wasteland - Roxton must face a series of challenges if he hopes to get out alive

Alone in the jungle, Veronica hears piano music and follows it to its source - a 19th century German village that has suddenly appeared in a fog choked valley. To her surprise, the handsome musician, Thomas Ducart, announces that he wrote the beautiful melody for her. Flattered by the musician's attention, Veronica takes him to the Treehouse, but Challenger is concerned

A mysterious visitor attacks Veronica, leaving an enigmatic ivory tile as his calling card. But when Marguerite finds the tile, she hides it from the others because only she knows what it means… one of the deepest secrets of her past has finally caught up with her, and now endangers her life and those of her friends. Back on the Plateau, with her friends facing death because of her actions in the past, Marguerite has no choice but to finally reveal the real reason she funded the Challenger Expedition, and what she has come to the Plateau to find

Using the Plateau's mysterious energy lines as a source of power, Challenger constructs a machine to send the explorers back to London. But when he, Roxton, and Marguerite find themselves in the same place they started from, they conclude the machine is a failure and head back to the Treehouse-only to discover the Treehouse is gone! While investigating what else has changed, Roxton is captured by slavers with automatic weapons and stripped-down cars, and learns the shocking truth-he and his friends are in the year 2033, eighteen years after an apocalyptic war devastated every place on Earth except for the Plateau

When a lost archaeological expedition discovers a mysterious burial urn, the young student who opens it suddenly collapses in convulsions. Though she quickly recovers, Professor Hamilton, the expedition's leader, suspects she's contracted a disease from the urn's skeletal remains. He believes that's the only rational explanation for the inscription on the urn, warning that an evil demon is imprisoned within

Challenger, Roxton, and Marguerite take Finn to a cave where one year earlier a blinding light opened a doorway to another reality. Once inside, the explorers witness an eerie apparition of a man Finn recognizes and fears. But when Finn races from the cave, the three figures who follow are not her friends-they're Kayle, Una, and Rixxel, three demons who have taken the place of Challenger, Roxton, and Marguerite

Hoping to end starvation, Challenger becomes the first human subject to test his new experimental substitute for food. But his nutritional beverage is not as successful for him as it was for his lab mice, and he quickly becomes obsessed with discovering the reason why. Then obsession leads to madness as Challenger is confronted by two opposing hallucinations

When Challenger discovers the wreckage of a World War I transport plane, he's captured by its pilot, Lieutenant Drummond. Drummond has been stranded for five years since the crash, protecting the plane's cargo—a crate of iridium ingots stolen from the Royal Navy. Challenger is astounded to see the iridium because it had been intended for his secret wartime research

Led by a dream, Veronica touches her mother's pendant to a stone monolith. A flash of mysterious energy knocks her unconscious, causing her to relive her last days with her long-lost parents as a young girl. When she awakes, she's shocked to realize her new memories don't match what she's always remembered of that time

A peaceful day of exploration turns deadly when a sudden explosion traps Marguerite and Roxton in an underground chamber. Their only hope for escape is Challenger, but the same explosion has left him with no memory of who he is, or what has happened to his friends. Meanwhile, a contest of friendly rivalry between Veronica and Finn leads to an enigmatic discovery at the Treehouse, as another memory from Veronica's childhood is literally uncovered

Two days before Challenger's latest attempt to leave the Plateau by balloon, Veronica and Finn encounter a strange phenomenon and are briefly transported into the post-apocalyptic future of New Amazonia. Soon after, Roxton finds himself being chased by 17th-century Conquistadors while Marguerite is captured by Druids determined to sacrifice her in order to avert a mysterious storm which is fast approaching. As different planes of reality continue to collide, Veronica at last realizes the time has come for her to fulfill her destiny as Protector and wield her mother's pendant-the Trion