Overview: Dorno and Gleep spot the Snake Riders, who plan an attack from halfway across the planet, across the Boiling Sea. They warn the others and the Herculoids drive them back to their caverns, but Zara gets captured. Zok disguises himself as one of the Riders' giant snakes and Dorno disguises himself as a Snake Rider and they sneak in, free Zara, and seal off the passageway leading back to the Snake Riders' home.