Diego and Pola embark on their mission of fixing the fissure in the center of the Earth to avoid the seepage. They don't know that Violeta and Diego's friends will follow them towards the unknown adventure.

Diego and Pola manage to save everyone from a giant spider, but just when everything seemed to be going well... the cave floods and the currents break the group apart! Ana and Laura will have to survive quicksand; Diego, Violeta, and Pedro will feel claustrophobic; and Pola and Pompilio will have to deal with a toxic river. Martin discovers that Pompilio is a descendant of Gaspar Nadar.

After our explorers manage to save Diego from a cave in which he was stuck, Martin enlists Evelyn and Mauro's help to get to the Calderon's offices at the North Pole. That may be his only chance to save the children... and the whole world!

Andrea, Pipe, and Evelyn arrive at the North Pole. Martin investigates the North Pole base. He discovers that the Calderon family is pretending to be on a mission to save the Poles, but they are actually drilling the Earth in search of tungsten. They are the ones causing the magnetic imbalance! Diego and his friends face a T-Rex and have fun in an anti-gravity cave. The children find Pola and Pompilio.

The journey to the center of the Earth continues. A bridge with lava breaks as they are crossing it and Pompilio takes advantage of this to steal Diego's device. Martin executes his plan to destroy the Calderon's ultrasonic driller, but he is discovered. Diego and his friends save Pompilio, who gets electrocuted by the tungsten. The group reaches the center of the Earth and tries to repair its fissure.

Martin manages to survive the fall, and with Evelyn and Andrea's help, he destroys the ultrasonic driller. They stop the drilling to the center of the earth. Thanks to his device, Diego manages to seal the fissure and asks his grandmother not to erase his friends' memories. Pola agrees and only erases Pompilio and Claudio's memories. The Verne family returns home as there is an evil one lurking.