Another thrilling adventure for the ThunderCats, when they stage a daring rescue attempt that tests them to their ultimate limits. After the destruction of Thundera, Mumm-Ra discovers that three Thunderians have survived and are living in peace with their rescuers, the Berbils. Mumm-Ra enlists Hammerhanc and his wicked crew to capture them, and uses his new captives to lure the ThunderCats to the one place that will rob them of their powers - Fire Rock Mountain. Determined to save their fellow countrymen, the ThunderCats rise to the challenge - but is the challenge too great?...