Lion-O, Panthro, and Snarf set out to look for more pieces of the Treasure of Thundera, and Mumm-Ra sets a trap for them. He freezes them in the caverns of cold on Thundera. Meanwhile, back on third earth, the Luna-tacs, in need of another source of power for their ship, use exercise machines to power it up. They capture the other Thundercats and force them to workout on the machines to power up the ship. The Thundercats manage to overwork the power supply, and escape from Sky Tomb. Back in the caverns, Snarf manages to get the sword of omens to Lion-O with his tail, and they escape and return to third earth.
Elenco: Bob McFadden , Larry Kenney , Earl Hammond , Lynne Lipton , Earle Hyman , Peter Newman , Gerrianne Raphael , Doug Preis , Will Friedle , Emmanuelle Chriqui , Kevin Michael Richardson , Matthew Mercer .