"Detektiv Conan: Full Score of Fear" is a feature-length anime film that centers around a high-stakes mystery involving a series of orchestral performances and a string of murders. The narrative begins with the renowned pianist Akemi Sono preparing for a concert at the newly constructed Bell Tree Concert Hall. Conan Edogawa, along with his friends and allies, attends the event, only to find themselves entangled in a complex web of intrigue.

The plot thickens when a series of cryptic messages and threats are directed at the concert organizers and performers. These threats are tied to a tragic incident from the past involving a fire at a music academy, which claimed the lives of several students. As the concert progresses, a murder occurs, and Conan must unravel the clues hidden within the musical performances and the history of the individuals involved. The investigation reveals connections between the victims, the suspects, and the tragic fire, pointing to a motive rooted in revenge and unresolved grievances.

Key characters include Conan Edogawa, whose sharp deductive skills are crucial in solving the case, and his allies, such as Ran Mouri and Kogoro Mouri, who provide support and assistance. The suspects include members of the orchestra, the concert hall staff, and individuals linked to the music academy tragedy. Each character has a role in the unfolding mystery, with their actions and backgrounds contributing to the intricate plot.

The film builds tension through a combination of suspenseful musical sequences and dramatic confrontations, culminating in a climactic resolution where Conan exposes the culprit and their motives. The narrative emphasizes themes of justice, redemption, and the enduring impact of past traumas, all set against the backdrop of a high-profile musical event. The story concludes with the resolution of the case, leaving the characters to reflect on the events and their implications.