Lion-O, Lynx-O, Snarf and Tygra go to the Crystal Canyon, thinking the Lunataks somehow got the Treasure of Thundera. While there, they encounter Aluro and Chilla. The two Lunataks trick the Thundercats by confusing them using with their reflections. They knock out the Thunderstrike and cause it to crash. Lynx-O is seriously injured and Lion-O is knocked unconscious. Tygra and Snarf find the Keystone and when Tygra holds the Keystone, he becomes convinced that it is making him more powerful. He uses it to restore the Thunderstrike, and heal Lion-O and Lynx-O. They return to the Lair and the other 3 Thundercats learn Tygra has become seriously addicted to the Keystone. When they try to tell Tygra he's become a slave to the Keystone, he doesn't believe them. Later in a battle against Aluro, Tygra thinks he's invincible, but Aluro proves him wrong and takes the Keystone from Tygra.

Starring:

Bob McFadden, Earl Hammond, Earle Hyman

Genre:

Action, Adventure, Animation, Family, Fantasy, Sci-Fi