Returning from their missions in deep space, Keith and the others pass by a planet where Hunk was stationed as a cadet. Hunk was sent there to help rebuild after an attack, but he had his food stolen by some street kids. Hunk eventually befriended the orphans and they helped each other. Now, when Hunk returns, Cossack follows him and captures Yellow Lion. The orphans help Hunk's desperate plan to recover his Lion before it's too late.

A ship of young pilots from Galaxy Garission crash lands on one of Zarkon's slave planets. All are enslaved except for Lt. Lorn, who is saved by a tribal girl with a grudge against Zarkon and a mysterious Fish Man. When Voltron arrives to free the young pilots, a Robeast attacks. The Fish Man is revealed to be one of Haggar's failed experiments. He grows to Robeast size and it's a Robeast versus Robeast battle to save the planet!

One of Zarkon's captains is imprisoned after he takes pity on some slaves. Now he is a slave alongside those he once oppressed. As they work on an alien planet, he is saved by a race of natives who live underground. When the Voltron force arrives, they decide to sneak in and free the slaves. But that's impossible without someone who knows the complex. Can they convince the former captain to help?

The capital city of Arus has finally been rebuilt, just in time for Zarkon to send an army of Crab Robeasts to level it. Keith and the others can't fight with all the citizens caught up in the destruction. Then the Robeasts dig into the castle, carving up the foundations. It is up to Princess Allura to travel deep inside the castle and uncover King Alfor's secret energy weapon to power up Voltron!

Lotor decides to build a new castle in secret, determined to take back the title of King. Under orders from Zarkon, Hagar destroys his castle with her new demolition Robeast. Pidge befriends a stray white cat to get back at the Space Mice, but it turns out to be the Robeast in disguise! When the monster destroys the Castle of Lions from the inside and captures Chedder, it's up to Voltron to hold off the creature while the other mice take to the sky and save their friend!

With the recent lull in the war, Galaxy Garrission finally has enough manpower to send a General down to Planet Arus to serve as a commanding officer for the Voltron Force. He disapproves of the team, their fun-loving attitude and their youth. He demands that they follow his orders and fight with small-unit tactics instead of forming Voltron. But Haggar's new Robeast is impervious to small-arms fire thanks to its new magic armor coating, and she's also sabotaged Green Lion!

With Zarkon and Lotor recovering from their big defeat against the forces of Planet Arus, local Drule warlord Cossack makes his move for glory. He assaults Planet Pollux, and manages to corner Bandor. Sven signals the Voltron Force and rides out on his horse to save the young prince. Keith and the others arrive to find that Cossack is working alongside an old enemy, and has a deadly trap waiting for Princess Alura.

Lotor activates his command center, Dark Doom Castle. Even with all his might, Voltron cannot fight off the entire castle alone. The team tries to hold on just long enough for Sven and Romelle to free the slaves. At the last moment, Coran flies to the rescue with the Castle of Lions in starship mode. While the fight rages, Sven sneaks into the evil castle alone to challenge Lotor personally!

Lotor has broken out of prison and taken over the throne of Planet Doom, Ashis father battles Voltron personally in the sky’s above! Sven and Romelle lead a team of commandos to blow up the Robeast laboratory. But Zarkon destroys the Blazing Sword, and Lotor surrounds Voltron with flying explosives, making it impossible for the team to move. The only one who can save them now is... Witch Haggar?

Lotor fails to capture Planet Arus and allows the Voltron Force to capture the Pulsar Cannon. For his gross incompetence, King Zarkon has his son imprisoned! Princess Allura and her alliance of local planets decide that now is their chance to launch a counterattack on Planet Doom itself. They disable Planet Doom's shield with a shot from the Pulsar Cannon, only to be faced with the ultimate Robeast: King Zarkon himself!