Tyrak is a ThunderCat of great physical skills, master of the Shoelrkin Blades (giant three prong throwing blades), completely deadly. Tyrak is Ben-Gali's best friend. They've known each other ever since they were kittens. But to the ThunderCats dismay, Tyrak has been hearing a voice in his head, for the past three years, a voice telling him to deceive and destroy the ThunderCats, especially their King, Lord Lion-O.
Who or what is this voice? It's no other than the evil Grune the Destroyer, who now wears the mystical Minds Eye Tiara recruiting an army of mind-controlled Thunderians that worships him as the true lord of the ThunderCats. And he wants Tyrak to head his war against the ThunderCats. Tyrak is still fighting Grune's control but is his mind strong enough to resist the power of the Tiara. ThunderCats are not all that easily controlled, but Tyrak has been having block out spells for five months now. Committing acts against his friend and fellow ThunderCats without his knowledge. How long before his mind is completely corrupted?