There'll Be a Royal Wedding - S1.E41

Furious at his defeat, Lotor throws Princess Romelle into the Pit of Skulls, from where no one has ever returned. But she is rescued by a wild man, an escaped slave who has been living alone in the caves under Planet Doom. Shocked, she realizes the wild man is Sven, former member of the Voltron Force! Romelle must help Sven reconcile with his painful past and take up the mantle of hero once again!