Tired of Slithe's incompetence as a leader, Vultureman summonsRatar-O, hoping that he will succeed in defeating the ThunderCats. The two head off in Ratar-O's spaceship, the Ratstar, to the Planet of Snarfs and capture Snarfer, binding him in special shackles. They then head to Third Earth where Ratar-O assumes command of the Mutants, much to the chagrin of Slithe. He then lets Snarfer escape, knowing that he will inevitably lead the ThunderCats to him.Snarfer runs straight to the Cats Lair where he meets his uncle Snarf who is delighted to see him. Inside the lair, Snarfer explains to the ThunderCats that when Thundera blew up, forty three of them commandeered an old Mutant tanker to an empty planet. As Snarfer is explaining about the Planet of Snarfs, Ratar-O pulls him to Castle Plun-Darr using the Rat's Eye to attract the cuffs that he put on Snarfer.The ThunderCats set out after Snarfer in the ThunderTank, leaving Wilykit and Wilykat to guard the lair. Unbeknownst to them, they are driving straight into an ambush set by Ratar-O who uses the Ratstar's scramblers to disrupt the ThunderCats' communications including the Sword of Omens' "Sight beyond sight".The Ratstar then attacks the ThunderTank, first firing the Barri-cannon at it and then turning a pile of rocks into a Rock Giant using the "Molecular Mutator". The ThunderCats manage to overcome all of these until Ratar-O fires the Void Charges which hit the tank and damage its main thruster. As Panthro tries to repair it, Lion-O distracts the Ratstar by drawing its fire towards him. He uses the Sword of Omens to counter the ship's fire and finally fires a beam from the sword which damages the Ratstar, causing it to crash. Having defeated the Mutants, the ThunderCats head to Castle Plun-Darr and free Snarfer.Back at Cats Lair, Panthro and Lion-O are finishing their newest vehicle, the Feliner, which will enable the ThunderCats to travel into space. However, Panthro explains that without a "Hyper Space Mega Condenser", the spaceship will not be operational. Snarf then suggests that they obtain the part from the wreck of the Ratstar.