S1, E1: Led by the maverick Professor Challenger, a party of explorers leave behind the smog and gaslight of turn-of-the-century London and search for a forgotten plateau deep in the uncharted regions of the Amazon jungle. Challenger is joined by Professor Summerlee, his arch academic rival, and as the expedition progresses the Professors bicker. Edward Malone, a reporter from the Daily Gazette, records their progress, whilst Lord John Roxton, big-game hunter and adventurer, leads the way, and missionary’s daughter Agnes Cluny helps with her knowledge of local customs. Eventually they attain their goal. But just as they reach the summit, they are betrayed by one of their number. The Reverend Theo Kerr Agnes' uncle, destroys the bridge they have built onto the plateau, leaving the group isolated, with no way back down!