Angered by Yurak's failures, Zarkon tasks his evil witch Haggar to send a robeast to Planet Arus, in hopes of capturing the five space explorers who escaped him and destroy what was left of any hopes to resurrect Voltron. Haggar sends her best robeast to Arus.

On Arus, the newly formed Voltron Force watches helplessly as Yuraks forces attack Arus, while Coran reluctantly keeps the secret of the Lion ships to himself. Pidge decides to head out by himself to see exactly how near Yurak's forces are getting to the castle.

Coran then reveals that the only way to activate the slumbering machines, is to locate the 5 mystic keys that can operate them. To Allura's surprise, he tells them that the keys were entombed with her father, the late King Alfor. Together, the members along with the Princess, make their way to the where King Alfor is entombed, and upon etnering the crypt, King Alfor's ghost makes his presence known to them. He shares with them his appreciation that five young strangers are willing to devote their lives to the protection of Arus.

Unfortunately, to their dismay, only four keys are found with King Alfor, meaning that Voltron can't be formed, since the key to the Black Lion is missing. Reluctantly, the team take the four lions ships; Blue, Red, Yellow and Green , hoping to thwart the forces of Yurak. They are able to take out the many robot fighter ships and troops, but when Haggar's robeast finally lands on the planet, they soon realize that they are not prepared to handle a fight of this magnitude. Coran and the Princess watch in horror, as their new friends were easily defeated by the meanacing robeast.