O Mundo Perdido Temporada 2 Episódio 14

The explorers have a strange guest at the Treehouse who impresses Challenger with his knowledge of geology. Meanwhile something attacks Challengers electrostatic accumulator. The explorers chase after a group of underground dwellers whom they believe to be the culprits. Their guest turns out to be one of them, and the explorers are soon taken hostage. It turns out that the underground dwellers need Challengers scientific expertise to help them evolve above ground.