A mysterious note accusing a student of being a witch triggers a chaotic investigation within a boarding school where magic is strictly prohibited. The protagonist, a young student, must navigate the mounting paranoia and suspicion that grips the school as everyone attempts to identify the secret practitioner. Opposing them are the rigid societal structures that fear magic and the looming threat of the Inquisition. The narrative unfolds through a multi-perspective framework, capturing the shifting alliances and hidden agendas of the students and staff.

This work is widely regarded as a clever subversion of the traditional school story, blending humor with a sharp critique of institutional intolerance. Readers often highlight the intricate world-building and the author's ability to balance a large cast of characters without losing narrative focus. The story's exploration of identity and the consequences of systemic fear resonates as a central thematic pillar. It remains a staple of the series, praised for its imaginative premise and the seamless integration of magical elements into a grounded, albeit alternate, reality.