ThunderCats

Lion-O, always outdone by his adoptive older brother Tygra, undergoes the ritual to be chosen by the Sword of Omens as the next king of Thundera. His father, Claudus, does not feel his son is ready because he is too lenient and easily distracted by flights of fancy like the myth of ancient technology. Soon after, King Claudus welcomes the return of his friend Grune and holds a celebration in both his honor and in memory of the fallen Panthro. During the event, Lion-O defends a pair of captured Lizards and convinces his father to release them.

An unforeseen betrayal by a former comrade brings destruction upon the Cat Kingdom. While King Claudus leads the fight against General Slithe and his lizard army, the evil sorcerer Mumm-Ra attempts to seize the Sword of Omens.

After escaping their destroyed city with the Sword of Omens, the team encounters the Fishmen, who sail the quicksand sea in search of a massive sea creature. The ThunderCats’ quest is to find the Book of Omens … but Lion-O is more interested in revenge on Mumm-Ra.

While traveling through the woods, the ThunderCats come across a group of Petalars - small plant-like creatures whose lifespans are only one day. Lion-O befriends the young Emrick as he and the others try to figure out a way out of the woods and return the Petalars to their home. Meanwhile, Slithe and his lizard army are hot on the ThunderCats' trail to eliminate them.

The ThunderCats accompany Panthro to Cloud Peak Mine to search for Thundrilium for the Thundertank. Along the way, Panthro and Grune's past is explored, from their first encounter to the reason behind Grune's betrayal.

The ThunderCats continue their quest for the Book of Omens, which leads them to the fabled Tower of Omens. However, they will first have to get past a series of deadly traps in order to reach it. Meanwhile, Mumm-Ra grows tired of waiting and forces Jaga to reveal the Book's location, and plans to go there himself to take it at all costs.

Lion-O ventures into the Book of Omens where he becomes the incarnation of his renowned ancestor, the valiant Leo, who led the rebellion against Mumm-Ra in a previous millennium.

As Tygra and Panthro work on the ThunderTank, Lion-O is searching for supplies and encounters a mysterious Drifter who helps teach a few important lessons. After showing off The Sword of Omens in town, Lion-O is challenged by a man known as The Duelist and must overcome himself in order to win.

The ThunderCats meet the mysterious beings who had helped them during the night and they turn out to be the Berbils, or Ro-Bears. The Berbils treat the ThunderCats with great hospitality until the village is attacked and some of the Berbils are captured. The ThunderCats help their new friends and a battle for freedom ensues.

The Cats track the location of the first stone to the mystical Elephant Village, but Lion-O can't find the specific location and the forgetful Elephants no longer remember where it is.

Sent by the Elephants to the Forest of Magi Oar, Lion-O must learn to master Sight Beyond Sight before returning to the Elephant Village. The Cats encounter a group of paper warriors with a dark secret.

The Cats are ready to retrieve the stone from the "Astral Plane" in the Elephant Village, but find it overtaken by Grunea and Mumm-Ra's forces. Plus, Tygra and Cheetara's early relationship to one another is revealed.