The gang takes a vacation to Hawaii where, unbeknownst to them, a nearby volcano is about to erupt thanks to an ancient amulet possessed by the evil Queen Medula. The descendant of Medusa, with her servant Kumo, plans to turn all of the investigating scientists to stone and sell them to the highest bidder, but Fangface, Fangpuss, and Puggsy overhear here scheme. The gang has to defeat Medula and rescue the scientists... without being turned to stone themselves.
The gang gets lost on a sea cruise after letting Sherman navigate, and he beaches their boat on the mysterious Spider Island. Baby Fangs goes exploring, drawing the entire gang into the clutches of a giant spider, who proceeds to ensnare Fangface and Fangpuss in a giant web and then drops the rest of the gang into an underground lab. There they come face to face with Dr. Lazarus Web, who has created a serum that can turn ordinary insects into giant monsters that do his bidding. He leaves the gang imprisoned in a net of webbing and takes his giant spider to New York, where he hijacks an entomology laboratory. Fangface and Fangpuss rescue their friends, and the gang travels to New York in an attempt to stop Dr. Web's plans.
Dr. Ortega and his assistant Carmen are hit with a shrink ray and captured by the Skullmen of the swamp, who want the archaeologists' help in finding the ancient tokens that gave the Skullmen's ancestors super powers. The gang tries to rescue Dr. Ortega and Carmen, but in the attempt they too are shrunk and imprisoned in a metal cage. With Fangpuss' help, they escape, and they have to find a way to rescue the archaeologists and return themselves to normal while avoiding giant sized dangers.
A parody of The Prince and The Pauper unfolds in the kingdom of Bavaria when the soon-to-be-king Prince Rudolph (who is the spitting image of Puggsy) is hypnotized and abducted by his ambitious cousin Count Basil. The gang just happens to be touring the castle to see the coronation, and when Puggsy discovers his likeness to the prince, the gang plans a switcheroo to make sure Count Basil doesn't ascend to the throne.
The diminutive Zeno uses his hypnotic ring to take control of the mysterious Filipino Cavemen, using the ancient strongmen to steal Professor Battack's newest invention: a power energizer that can make any man ten times his normal strength. Using the energizer on his caveman slaves, Zeno escapes to his secret airplane hangar, but he didn't count on the ingenuity of Fangface and his friends. Disguising themselves as cavemen, Fangface and Puggsy infiltrate the hangar with Fangpuss hidden in a spring-loaded club very similar to that of Captain Caveman, but Zeno is not so easily fooled.