Before the events of the Slayers TV series, Lina Inverse embarks on a journey to Mipross Island alongside her rival and companion Naga the Serpent. Initially drawn by the allure of hot springs, they become entangled in a sinister plot orchestrated by a mazoku named Joyrock. This malevolent being decimated the island's elven population years ago, absorbing their essence and leaving a trail of tragedy. Their quest takes an unexpected turn as they are joined by Rowdy Gabriev, an elderly mage driven by a vendetta against Joyrock for the massacre that claimed the life of his elven love. Together, they must confront this ancient evil and unravel the mysteries shrouding Mipross Island.