Inside Cats Lair, Panthro is tracking a giant meteor which has just entered Third Earth's atmosphere. Further analysis of it shows that it is composed entirely of pure Thundrillium and Panthro deducs that it must have been a part of Thundera. The ThunderCats are pleased with this discovery as their fuel supplies are running low. Panthro tries to bring it in but is unable to due to the lair's Thundrillium supplies being on the verge of depletion. He continues to track it on reserve power supply. The meteor flies overhead, scaring several of the inhabitants of Third Earth, like the Warrior Maiden s, the Living Ooze, some unicorns, and the Berbils, before eventually crashing into Hook Mountain.Lion-O decides to go after the meteor alone. Tygra warns him that the Snowmen of Hook Mountain are savage and proud but Lion-O is undeterred. Cheetara gives him a red cloak to keep him warm and the young lord sets off on his perilous journey. Shortly, he reaches the rugged snowy terrain at the foot of the mountain and unbeknownst to him,Jackalman is spying on him. As he continues onwards, Lion-O senses that someone is following him. It turns out to beSnarf who was worried about Lion-O and decided to secretly tail him. Both of them continue the journey to the top of the mountain.Meanwhile, Jackalman returnd to Castle Plun-Darr and informs his fellow Mutants that Lion-O is alone on Hook Mountain. Slithe thinks this will be a good opportunity to kidnap Lion-O and force the other Thundercats to do their bidding while they hold him hostage. When Monkian asks how they will reach Hook Mountain, Slithe responds thatVultureman would take them in his Flying Machine. Jackalman, unsure about the safety of the contraption, decides to not join them. So Slithe, Monkian and Vultureman take off in the Flying Machine.Back at Cats Lair, the Thundrillium supplies have completely depleted and the fortress is left in darkness. Panthro initially proposes that they just sit and wait until Lion-O signals them with the Eye of Thundera. Cheetara, however, sensing that Lion-O could be in danger, feels that they should go after him. Panthro agrees and the ThunderCats set off for Hook Mountain in the ThunderTank.Lion-O is still continuing his ascent up Hook Mountain and uses his Claw line to climb some of the more perilous cliffs. He and Snarf finally reach the summit where they see the Castle of the Snowmen. The drawbridge of the castle opens and Snowman emerges, armed with a lance and shield and riding Snowmeow. When Lion-O tells the Snowman that he has come for the meteor, the Snowman refuses to give it to him and challenges him to a duel. The two engage in battle and the Snowman knocks the Claw Shield out of Lion-O's hand. Then the spirit of Jaga appears and reminds Lion-O that Snowmeow is a cat and Lion-O, being lord of the ThunderCats, has power over all cats. At that instant, Snowman charges but Lion-O commands Snowmeow to halt which the big cat does. Snowmeow's sudden stop throws Snowman of the cat's back and into the Bottomless Chasm where he lands on a legde.Using his Claw line and the sword as an anchor, Lion-O climbs down the chasm to rescue the injured Snowman. Suddenly, the Mutants arrive in the Flying Machine and try to pull out the sword ut Snowmeow foils their plan by clawing and jumping on the wings of the mutant aircraft. Lion-O emerges from the chasm, carrying Snowman on his back. Slithe orders Vultureman to attack Lion-O who retaliates by using the Sword of Omens to call the other ThunderCats. Seconds later, the ThunderTank arrives at the scene, firing its lasers at the Mutants who make a hasty retreat.Snowman tells Lion-O that the young lord proved that he values honor, courage, and friendship, and so he has earned the meteor as well as the Snowman's friendship. Lion-O tells him that if he evers need help, the Snowman can call on the ThunderCats. The Cats bid farewell to Snowman and snowmeow and head back home in the tank.