In her vengeful desire to destroy Hercules, Hera unleashes more terrible beasts upon the kingdom of Mycanae. When the Erymanthean Boar attacks, young sheepherder Iolas tries to be a hero like Hercules. But, lacking strength, he fails miserably in his attempt to save his brother and sister from the fearsome boar. It's only Hercules' last-minute arrival which prevents disaster. Longing to be a hero, but feeling that he's a failure, Iolas returns to Hercules' side in hopes of learning the secrets which make him a hero. As our twosome confront the deadly "Horses of Diomedes" and the giant "Stymphanian Birds," Hercules becomes more and more impressed by Iolas' cleverness. But Iolas, convinced that what makes a hero is his strength, cannot see the value in this. In the end, when Hercules is forced to face the "River God," and when he appears to have met his match, Iolas finally understands that every hero has his own unique strength. Using his brains instead of his brawn, Iolas helps Hercules to outsmart the River God, and he becomes a hero in his own right.