The Mutants emerge from the wreck of the crashed RatStar andSlithe blames Ratar-O for their failure to defeat the ThunderCats. He goes so far as to challenge Ratar-O's authority, a move which greatly annoys Ratar-O and he immediately uses the power of his Rat's Eyesais to put Slithe and the other Mutants in their place. He then instructs them to build a Mutank from the wreck of the RatStar and they use it to drag the wreck to Castle Plun-Darr.
Inside Cats Lair, Snarf is contemplating leaving with Snarfer for the Planet of Snarfs but doesn't reveal his thoughts to the others just yet. He only tells Snarfer about his intentions and the two join the rest of the ThunderCats as they head out in the ThunderTank to obtain the "Hyper Space Mega Condenser from the wreck of the RatStar. Meanwhile, Mumm-Ra, who had been observing the activities of both the ThunderCats and the Mutants from his cauldron, decides to seize the Mega Condenser himself in order to lure the ThunderCats to him. He changes to his ever-living form and flies out of hisBlack Pyramid.
As the ThunderCats reach the wreck site, they are surprised to find the RatStar missing. Lion-O uses the Sword of Omens' "Sight beyond sight" to see that the Mutants had towed the wreck to Castle Plun-Darr, so the ThunderCats head there. As soon as they reach Castle Plun-Darr, the Mutants, led by Ratar-O, attack the ThunderCats using the Mutank. As the two tanks engage in battle, Lion-O slips out and enters the wreck of the RatStar to try and locate the Mega Condenser, only to find it in the possession of Mumm-Ra.
Mumm-ra flies out with the Mega Condenser but Lion-O snags Mumm-Ra's cape using his Claw line and he too is dragged out. Lion-O then pulls Mumm-Ra to the ground, causing him to drop the Mega Condenser. Seeing that he is no match for the Sword of Omens, Mumm-Ra retreats. Before Lion-O can get the Mega Condenser, Ratar-O reaches it and challenges Lion-O to a duel over the right to its ownership. The Rats Eye and the Eye of Thundera clash in a fierce battle but the Sword of Omens proves to be the more powerful one and Ratar-O flees. The ThunderCats collect the Mega Condenser and head home.
Back at Cats Lair, Panthro, Cheetara and the ThunderKittens are getting ready to take Snarfer to his home planet in the now operational Feliner. At that point, Snarf reveals his decision to leave with Snarfer, claiming that he isn't need anymore. This greatly shocks and saddens the ThunderCats, especially Lion-O who pleads with Snarf not to go but Snarf does not relent. The Feliner takes off but moments later returns and Snarf, having decided to stay after all, runs out of the spaceship and into Lion-O's arms.