"Detective Conan: Zero's Executioner" is a feature-length anime film set within the "Detective Conan" franchise. The story revolves around a high-stakes terrorist attack targeting the Tokyo Summit, an international conference held at the newly constructed Edge of Ocean facility in Tokyo Bay. A series of bombings disrupt the event, leading to widespread chaos and a race against time to uncover the perpetrators. The narrative intertwines the efforts of Conan Edogawa, a brilliant young detective trapped in a child's body, and Rei Furuya, also known as Toru Amuro, a skilled investigator with a hidden agenda tied to his undercover work with the Public Security Bureau.

The plot begins with the arrest of a suspect linked to the bombings, but the investigation takes a dramatic turn when evidence implicates Amuro as the mastermind behind the attacks. This revelation creates tension among the characters, as Amuro's dual identity as a member of the secretive Black Organization complicates his motives. Conan, along with his allies, including Kogoro Mouri and the Tokyo Metropolitan Police, must navigate a web of deception to determine whether Amuro is truly a villain or a victim of a larger conspiracy.

Key characters include Conan Edogawa, whose deductive skills and resourcefulness drive the investigation; Rei Furuya (Toru Amuro), whose complex loyalties and enigmatic actions keep the audience guessing; and Kogoro Mouri, whose involvement adds both comedic and dramatic elements to the story. The film also features appearances by familiar characters such as Ran Mouri and the Detective Boys, who contribute to the narrative in supporting roles.

The story builds toward a climactic confrontation at the Edge of Ocean facility, where Conan and his allies must prevent a catastrophic explosion while uncovering the true orchestrator of the terrorist plot. Themes of trust, betrayal, and the blurred lines between justice and vengeance are explored as the characters grapple with their own moral dilemmas. The film maintains a fast-paced narrative, blending mystery, action, and suspense, while staying true to the core elements of the "Detective Conan" series.