Defeated by the Voltron Force, King Zarkon grows wary of his charges continuous defeat against the mighty robot defender. Haggar suggests that they hold a contest between her robeast monsters to determine one that would go to Arus and battle against the Voltron Force. They hold a battle and one such monster suceeds against the other monsters. Haggar then turns him into a giant robot monster, and sends him with Yurak and his forces to Planet Arus.

On Arus, the Voltron Force are seeking help among the citizens of Arus, hoping that they will be brave enough to come out of hiding. Though, the people are still afraid and refuse to come out of hiding. It is then that Yurak attacks Arus, so the Voltron Force launch their lion ships.

Quickly they realize that this robeast monster is much stronger and faster than their previous encounter and quickly lose their advantage. While the monster confronts Voltron, Yurak takes the opportunity to attack the Castle of Lions directly. Allura and Coran flee to the underground tomb of her father, there his spirit reveals a secret. Allura presses a button in the crown of his tomb and suddenly, a new and improved castle emerges from the ruins of the old one.

Princess Allura comes to the aid of the Voltron Force by taking up one of the gun cannons on the side of the new Castle. There she wards off Yurak's attack with direct hits to his ship, then focuses her attack on the robeast. This gives the Voltron Force their opening to attack the monster and then destroy him.