A ship of young pilots from Galaxy Garrison 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 its' a Robeast versus Robeast battle to save the planet!