"Slayers - The Motion Picture" is a feature-length anime film set in the fantasy world of the "Slayers" franchise. The story centers on Lina Inverse, a powerful and brash sorceress, and her companion Naga the Serpent, a rival sorceress with a flamboyant personality. The narrative begins with Lina and Naga encountering a mysterious young girl named Lemia, who is being pursued by a group of knights. Lemia claims to have lost her memory, and the duo reluctantly agrees to help her uncover her identity.

As the story progresses, it is revealed that Lemia is actually the reincarnation of a powerful sorceress who once sealed away a destructive demon known as Shabranigdo. The knights pursuing her are part of a cult seeking to resurrect Shabranigdo, believing his return will bring about a new era of chaos and power. Lina and Naga must protect Lemia while unraveling the truth behind her past and the cult's sinister plans.

The film explores themes of identity, sacrifice, and the consequences of wielding immense power. Lina and Naga's dynamic is characterized by their constant bickering and competitive nature, which provides comedic relief amidst the darker elements of the plot. The narrative builds toward a climactic battle as Lina and Naga confront the cult and the resurrected Shabranigdo, testing their magical abilities and resolve.

The film maintains the tone of the "Slayers" series, blending action, humor, and fantasy elements. Lina's signature spells, such as the Dragon Slave, are prominently featured, showcasing her prowess as a sorceress. Naga's over-the-top personality and provocative attire add to the film's comedic and adventurous atmosphere. The story concludes with Lemia regaining her memories and making a pivotal decision to ensure the demon's defeat, leaving Lina and Naga to continue their journey as unlikely allies.