A space explorer, previously thought lost in space, returns to Earth and joins four teenagers in a search for a giant robot lion.

The Blue Lion delivers the team to an alien planet where they discover a mysterious castle. Inside, they awaken an alien princess who sends them on a mission to find the remaining lions.

The castle is attacked by an alien battle cruiser and the new Paladins must form Voltron.

When the Paladins start to lose focus, Princess Allura puts them through training; with cooperation, the Paladins can learn how to form Voltron.

Shiro is forced to draw from painful memories from his past when a massive, evil robot becomes a threat.

As a Paladin threatens to leave the team, invaders get inside the castle and destroy its power crystal in hopes of stealing Voltron.