Hanna-Barbera animation about the famed whale and his pal Scooby the seal, who undertake undersea adventures. On land, a prehistoric boy becomes the invincible Mightor when troubles arise.
Grok steals the Golden Rok, which has the ability to control any animal. It falls out of his pouch as he is leaving and hits Little Rok on the head. While fighting a dinosaur, Little Rok discovers the power of the Golden Rok. As he is experimenting with it, Grok returns and steals it back. Tor hears animals fighting in the area that Little Rok had gone. He turns himself into Mightor and heads off to investigate.
Iguanis of the Iguana Men orders two of his men to capture Tom and Tubb. They are very aware that Moby is their guardian and set a trap to capture them. Scooby alerts Moby that the boys have been captured so he chases after the Iguana Men to try to save his friends.