Zandor and Dorno rescue a man floating in the river who says he is from Gravite Island and tells them that a villain has taken over the island. The Herculoids go to investigate and are attacked by giant gravite creatures. The creatures are being created by Lotak, who wants the village because of its large deposits of gravite. Zok destroys the machine Lotak uses to make his creatures and Lotak is destroyed when his energy ray backfires. Malak sends his Metal Apes to attack the Sea People. Dorno is shot off of Zok by one of the creatures. Zandor and the Herculoids destroy the Metal Apes. A damaged Metal Ape returns to Malak's headquarters and is followed by the Herculoids. The Herculoids destroy the remaining Metal Apes and Zok causes a steel beam to fall on Malak and his assistant.