On the distant planet of Mythrandir, the wise Empress Opal keeps watch over the Great Crystal - a legendary relic containing untold power. But when the sinister Zok nearly takes the crystal for himself, the empress sends its five remaining gems to Earth. After hurtling into the city, the gems transform a brutally lame band into geode-powered rock stars! And that's not all, these rockers are suddenly whisked away on an impromptu galactic tour to save Opal and the people of Mythrandir as their new champions - the Stone Protectors!