I've seen several episodes of this program and I think it is a wonderful series that more kids these days should watch. The main characters in the show are Lion-o, Panthro, Cheetara, and Tygra. The beginning of the story is the simplest of stories you can tell they took elements from Superman's origin and adapted it for the series; the only difference is that instead of one survivor of an exploding planet. there are five.
Their leader, Jaga, flees with the survivors on a small spaceship with no clear destination. Their leader programs it to land on the nearest inhabitable planet, which we find out later is called "third earth" in this period of time. However, we are shown in subsequent episodes that it is our earth. They land on earth that is several thousand years older than the one we currently inhabit. The main antagonist of the Thundercats series is Mumm-ra ,an ancient human sorcerer from Egypt. He serves entities called the ancient spirits of evil. He sees himself as the ruler of earth in this time, though there are many other evil individuals on this planet. However, during this time, he is by far the most powerful force of evil on the planet.
Mumm-ra takes many forms and many different things to the different cultures that are found on earth. At this time, the spirits of evil have granted him vast knowledge of magic and highly advanced magical spells. While he is the most powerful force of evil on the planet, he is afraid of his own reflection, which is weird. At least the first couple of seasons, the Thundercats have one major advantage over him: The Sword of Omens. This sword is wielded by the leader, but interesting thing is, the leader of the Thundercats has physically aged due to sleeping in a time capsule from age 12, however has not mentally aged. So essentially a 12 year-old brain in a mature body. Thankfully he matures slowly but steadily during the series, and learning from his mistakes.
We learned later on in the program that the leader of the survivors inadvertently causes their planet's destruction. The mutants who chased the ThunderCats to third earth also crash, but are summoned by the sorcerer to his pyramid to forge an alliance to crush the ThunderCats. There are many times when Mumm-ra comes close to victory, but somehow fails the last minute.
I feel the show had a good message all around. Every episode has the current Lord of the ThunderCats learn a lesson, and I think he learned the best way anyone can learn a lesson which is through trial and error. There is a newer version of the ThunderCats that was made in 2011, which is also a good series, but I think the 1985 version was a slightly better series. It had a very simplistic message and I believe that message was that evil only triumphs if good men do nothing. Or to put it another way, evil is only successful when good creatures are ruled by fear, and ThunderCats showed us that it doesn't take a large team to make a difference. It's all a matter of how someone utilizes what they have, and make whatever kind of difference they can.