Plot: Mumm-Ra learns about the Treasure of Thundera and the Sword of Plundarr (Jaga had beaten Ratilla, who owned the Sword, and then buried the sword deep underground), and he and Ma-Mutt ""travel back in time and space"" to explore the debris of Thundera and look for the sword, which causes the planet to reform. The Thundercats find out about this and must make the journey to New Thundera to stop Mumm-Ra