|“||"It would've been mine if it hadn't been for those meddling kids!"||„|
|~ - Professor Wayne|
Professor Wayne dressed up as a Caveman to get his colleague's invention that could talk to aquatic animals.
While fishing at a beach, Shaggy snagged and pulled ashore a giant block of ice containing a frozen caveman. Velma recognizes it as a two million-year-old caveman discovered in the Arctic and washed over the side of a research vessel during a storm. The kids take it to Oceanland and leave it with two scientists, Professors Wayne and Engstrom. After they leave, someone turns a space heater onto the caveman. At the malt shop, Shaggy remembered that he left his fishing tackle at Oceanland, and the gang returned to pick it up. They found the doors ripped off their hinges, Wayne's torn parka, and the caveman thawed out and missing. The phone was broken, so the kids decide to investigate. They follow giant caveman tracks to the dock, where they see Engstrom working a strange device and seemingly talking to a porpoise. He takes fright and flees into a shack when he hears Scooby creeping up on him. When Freddy opens the door to the shack, they discover the angry caveman, who chases them all about Oceanland.After they escape, Velma finds a map showing the currents off Oceanland and an object anchored offshore. She, Shaggy and Scooby take a boat out, where they find a fishing boat. They are locked inside it with an ice machine that is churning out giant ice blocks full blast. They escape just before being crushed by the ice, only to find that their boat has been scuttled, so they paddle back to shore on an ice block.
Freddy resolves to catch the caveman and has Shaggy and Scooby (dressed as fish) lure the caveman to a spot where he and the girls can drop a net on him. But Daphne falls, pulling everyone else down into the net. The caveman chases them again but is caught when he falls into the tank holding the giant clam. They pull him out and unmask him as Professor Wayne. Wayne had heard about the loss of the Arctic caveman and had constructed his own "frozen caveman" at the fishing boat, with the intent of letting it drift down to Oceanland. After its recovery, he melted it with an electric heater, and then disguised himself as the caveman with the idea of getting rid of Ingstrom and stealing his invention: a revolutionary marine life communicator. After Professor Wayne was taken away by the sheriff, Mystery Inc. heads to the malt shop where Scooby-Doo uses the caveman costume as a dance partner.