Inside Castle Plun-Darr, the Mutants are extremely dissatisfied with the food that is being served to them by their Lizard Cook. Monkiansuggests that a "woman's touch" is needed in the castle and Slithe, concurring, orders the simian to find a few servants.Nayda, one of the Warrior Maidens of Third Earth, is fishing when Monkian suddenly abducts her. Nayda cries out for help and in the blink of an eye, her elder sister, Willa, armed with bow and arrows, arrives and foils Monkian's plans, sending him fleeing into the forest. The two sisters are upset at the way their world has changed after the sudden arrival of the two alien groups.Back at Cats Lair, Lion-O decides to take the ThunderTank for a joyride, inspite of Snarf's objections. Lion-O loses control of the tank and it zooms around erratically with the young lord still inside. Hearing all the commotion, Panthroemerges form the lair, jumps into the tank, and stops it just as it is about to go over a cliff.Panthro is less than happy about Lion-O's antics and points out that the Thundrillium supply is dangerously low and without it there will be nothing to fuel the tank or the lair. The ThunderCats decide that they should venture out into their new world and search for Thundrillium. Panthro provides each Cat with a Thundrillium Detector which would start to flicker whenever the substance is detected nearby. The ThunderCats each set out in a different direction.Having overheard the ThunderCats talking about their dwindling fuel supplies, Monkian returns to Castle Plun-Darr and reports this information to his fellow Mutants. Seeing this as an opportunity to defeat their feline nemeses, they set-off to prevent the ThunderCats from succeeding.While passing through a forest, Lion-O comes across WIlla being attacked by a giant dinosaur like creature known as theLizarthon. Lion-O scares it off using his Claw Shield. He introduces himself to her but she remains suspicious of him.Meanwhile in his search for Thundrillium, Tygra wanders into a strange cave which is giving a strong reading on his detector. Unbeknownst to him, he has entered the Cave of Time and anyone who ventures in there, ages rapidly until they die. Tygra begins to age at an accelerated rate and upon realizing this he tries to turn back but he has become too weak to walk out of the cave.Still in the forest, Lion-O is ambushed by the Mutants but this time Willa saves him by firing arrows filled with sleep gas at the Mutants who make a hasty retreat. As Lion-O is thanking WIlla for her help, the Sword of Omens warns him about Tygra. Willa tells him that only someone who is fast enough to avoid the cave's effects can bring Tygra out safely. Lion-O immediately thinks of Cheetara and summons the other ThunderCats.Panthro, Cheetara, Lion-O and Willa arrive at the Cave of TIme and Cheetara sprints in and brings Tygra out with her in a matter of seconds. Willa tells them of a pool that can heal Tygra called the Geyser of Life. The group decide they need to get Tygra to it as fast as possible. When they arrive, they find that the geyser is guarded by the fierce Wing-ed water snakes. Lion-O and Cheetara distract the flying serpents while Tygra enters the waters and comes out young again.