Young Katherine and Young Tommy each try to retrieve their Zeo sub-crystals. Kat returns to Australia, and finds her good heart tested when forced to choose between helping an elderly woman and accomplishing her mission. Tommy gets a lesson in his Native American heritage from a wise old man called True of Heart. Back in the present, Billy faces another setback in his attempts to rehydrate the Aquitians. Lord Zedd and Rita seek to summon the Emperor of the Dark Waters, the Hydro Hog, from Aquitar to aid them in stopping their mutual enemies, the Alien Rangers. Meanwhile, Rito & Goldar get a premature start to their implosive goals.