The comic begins with Snarf talking to the Book of Omens. It is clear that Snarf is not mentally stable because he is holding both sides of a conversation about using a key to open the book of omens. Snarf uses the key to enter the book and finds Lion-o training. Lion-o believes he as been in the book for a day, but Snarf tells him he has been in the book for five years. Snarf then recounts that during the first year of Lion-o's absence the Thundercats and Thundera thrived. The Thundercats rebuilt their civilization with Panthro in charge. Thundercats returned to Thundera, and the civilization began to boom. One night Mumm-ra attacked with hundreds of mutants from Plunddar. In that one night Mumm-ra and the mutants killed, conquered, and enslaved all of the Thundercats. Snarf escaped, seemingly under Mumm-ra's nose, with the Book of Omens. Mumm-ra gave Slithe the key to the book and told him to destroy it. Slithe discarded the key in a location he thought no one would find it. After five years, Snarf located the key.
Lion-o and Snarf return to Thundera and the devastation and change in Thundera is immediately evident. There are statues of Mumm-ra and Ma-mutt, mass devastation of the landscape, and no Thundercat structures standing. Lion-o uses the Eye of Thundera to locate Panthro and sees that he is being forced to work in the mines. At this point the comic turns to the point of view of Mumm-ra. Mumm-ra, speaking to Ma-mutt, explains that he has been bored, but he is excited now that Lion-o is back. It is clear that Mumm-ra knew that Slithe would not destroy the key and that Snarf would free him. Mumm-ra calls his servants into his chambers for something, and the audience sees Wilykit and Wilykat as adults.
