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

The Quest nemesis, Dr. Zin, sends a giant, cyclops, robot spider (by flying saucer-like craft) to a U.S. government research facility in the American Southwest to steal the secrets of a ray gun project on which Dr. Quest is working.

While investigating a mysterious illness in India, Dr. Quest discovers an underground nerve gas factory (operated by a master criminal and protected by hazmat-suited guards) hidden high within a remote mountain range. (Flashback episode, recounting the adoption of Hadji.)

While on an Archaeological expedition to an ancient Mayan city in the Yucatan Jungle, Dr. Quest is threatened by a ruthless British treasure hunter (and his native Indian confederates), searching for riches in the same ruins. 

While investigating a bar of fake gold from a supposedly exhausted mine in India, Dr. Quest uncovers an alchemist counter fitting ring (conceived by his nemesis, Dr. Zin, and operated from the palace of a maharajah impostor) that could damage

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.

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 artifact in Egypt.

A foreign submarine crew races Dr. Quest and his recovery team (aboard an American icebreaker) to a downed experimental missile on the arctic ice cap. Note: First appearance of Hadji.

While investigating the disappearance of shipping 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 old shipwreck. Note: Hadji does not appear in the

This episode in essence is the Series Finale of three shows (the Scooby-Doo segments of Scooby’s All-Stars, The Scooby-Doo Show, and – unofficially – Scooby-Doo, Where are You!). The gang goes to Canada at a newly deserted village of Bottomless Lake.

The gang meets Jimmy Pelton, a star tennis player, while cruising England. Jimmy has been cursed by the Warlock Anthos that if he plays in Wimbledon he is doomed.

The gang arrives at Puerto Rico to visit the ancient fortress El Moro. While there, the kids run into a ghostly commander named Juan Diego who warns them to stay away from his creepy fortress.