When Dr. Quest's site is under attack by a UFO and the aliens succeed into kidnapping Jonny and Hadji, it's up to Dr. Quest and Race to rescue the boys. Also Benton and Race suspect the aliens are bogus.
Dr. Zin is back and kidnaps a rocket specialist who is working for Dr. Quest. The captured specialist has a daughter who rushes to the Quests and begs them to save her father.
Jonny, Dr. Quest, Race and Hadji are on a recovering operation of a World War II submarine that vanished in 1945. When the team found the submarine, inside it there was a time machine that sends them back to 1945.
An orange-furred frozen Viking guardian ape was discovered by the Quest team. They name it Vikong ('Viking' + 'King Kong'). The creature is friendly, but the local villagers and greedy land developers don't see it that way. The Quests must help to protect the creature.
An oil-drilling operation discovers a passageway to the center of the Earth. The Quests are on the tracks of the scoundrels when they stumble upon a creature of living rock named Hardrock that joins forces with Jonny and his friends.
The Quest team investigate the disappearance of a scientist reputed to have fallen victim to clay warrior guardians angered by his disturbing their burial grounds in Tibet.
When a computer pilot is built, Race believes that nothing can fly better than a human one. But during a test flight Race is kidnapped by a former rival, who is a man badly injured and using robotics to replace his missing body parts - Skyborg. His mission is to steal Quest's computer guidance system on behalf of the foreign power that gave him his parts.
The delegates at a peace conference in India turn against one another after they were plagued by hallucinations. While Dr. Quest acts like a mediator, Jonny, Hadji and Race are looking for Hadji's old mentor, who happens to be kidnapped and his mental powers are used for evil.
The Quests must deal with a plant creature that is responsible for the disappearance of a number of people in a nearby woods. The creature converts its victims into similar plant-creatures and soon an army of the vegetoids starts marching forth.
