While investigating the disappearance of multiple ships in the Sargasso Sea, Dr. Quest discovers a secret laser base (operated by a foreign provocateur and protected by lizard-suited scuba divers) hidden aboard an 18th-century shipwreck.

A foreign submarine crew races Dr. Quest and his recovery team (aboard an American icebreaker) to a downed experimental missile in the Arctic ice cap.

A former archaeologist friend-turned Arab nationalist revolutionary named Ahmed Kareem, who is being stalked by a vengeful mummy, attempts to frame Dr. Quest and Race for the theft of a priceless Egyptian artifact.

While going to the aid of a captive fellow scientist in the Amazon jungle, Dr. Quest is abducted (for ritual sacrifice) by a tribe of hostile native warriors.

While on an archaeological expedition to an ancient Mayan city in the Yucatán jungle, Dr. Quest is threatened by a greedy, ruthless British treasure hunter named Perkins and his native confederates, searching for riches in the same ruins.

While investigating a mysterious ailment in India, Dr. Quest discovers an underground nerve-gas factory (operated by a criminal mastermind and protected by hazmat-suited guards) hidden high within a remote mountain range.

Dr. Zin sends a large, black, cyclopean, four-legged spider-like robot (by a flying saucer-like craft) to a U.S. government research facility in the American Southwest to steal the secrets of a para-power ray gun on which Dr. Quest is working.

An impostor disguised as Race is infiltrated into Dr. Quest's expedition to gather a rare pharmaceutical plant by Dr. Zin (who covets the plant's potential mind-control properties) in the jungles of Thailand.

After an emergency landing in the Andes Mountains, Race is challenged to an aerial dogfight by Baron Heinrich von Frohleich, an old German fighter ace of World War I fame (who keeps a collection of vintage aircraft at his Bavarian-style castle in South America). The Baron's machine guns, however, are loaded — Race's are not.

In the Caribbean Sea, a new cook aboard the Quest research vessel betrays his employer to a gang of Mexican pirates (seeking a sunken treasure chest, discovered by Jonny).

While researching marine biology in the Caribbean, Dr. Quest encounters a phony witch doctor, who is protecting a secret submarine base (under construction by a criminal contractor) with his supposed voodoo powers.

When the members of his team descend in a plane crash over uncharted jungle territory, Dr. Quest must rescue them (with the help of local authorities) from a tribe of hostile Pygmy warriors.

On a visit to Japan, Dr. Quest finds that an old biologist friend (having gone insane) is breeding over-sized carnivorous lizards for the purpose of hunting human prey.

While searching for a rare strategic mineral in the Amazon jungle, Dr. Quest and Race discover a prehistoric Pteranodon, trained by a wheelchair-bound slave driver to capture and guard native workers needed for his mining operation.

While investigating unusual tremors on a tropical island in the South Pacific, Dr. Quest and Race uncover a secret ray gun base (operated by Dr. Zin and protected by hovercraft-mounted guards) hidden deep within a local volcano.

While hunting for samples of petrified wood in the Canadian Rockies, Dr. Quest is threatened by a gang of lumberjacks (one of whom disguises himself as a werewolf) intent on protecting their gold-smuggling operation.

The Quest home compound in Florida is attacked by foreign (submarine-borne) agents, intent on stealing a new undersea crawling vehicle that Dr. Quest is developing for the United States Navy.

Jonny and Hadji are marooned (by shipwreck) on the jungle coast of the African continent, where they are adopted by a tribe of friendly brown gorilla-like apes who protect them from a pair of Australian poachers, intent on kidnapping them for ransom. When the poachers managed to abduct Dr. Quest and Race, Jonny and Hadji must persuade to the apes to help rescue them and defeat the poachers.

Dr. Quest responds to the distress signal from a fellow scientist, who has accidentally unleashed an (invisible) energy monster on a South Pacific island.

While doing atmospheric research in the African savanna, Dr. Quest uncovers an inaccessibly high plateau, populated by prehistoric cavemen, who have been trained as slave laborers for diamond mining by Klaus Heinrich von Dueffel, a Nazi war criminal in hiding.

While investigating the contamination and mutation of marine life in China, Dr. Quest discovers a secret missile base (operated by a rogue general and protected by treetop-posted guards) hidden deep within a local swamp.

On a visit to the castle residence of a fellow Norwegian scientist, Dr. Quest must help protect his colleague's latest invention (the anti-gravity generator) from a cat-burglar, disguised as one of a row of seven gargoyles on the roof, who regularly breaks into the estate.

Dr. Quest is kidnapped by a rival scientist who needs help with his experiments to develop gigantic (crab, spider, lizard) creatures at a secret Hong Kong-based laboratory compound.

During a trip to Nepal, a band of terrorists disguised as yetis attempt to overthrow the local spiritual/government leader (a Dalai Lama-style figure) who is an old friend of Dr. Quest's.

Responding to a maritime distress signal in the Java Sea (east of Indonesia), the Quest group is stranded aboard an abandoned freighter ship with an (amphibious) sea monster.