"Detective Conan" centers on Shinichi Kudo, a brilliant high school detective who is transformed into a child after being poisoned by a mysterious organization. Adopting the alias Conan Edogawa, he continues to solve crimes while concealing his true identity. Living with his childhood friend Ran Mouri and her father, private detective Kogoro Mouri, Conan assists in solving cases by subtly guiding Kogoro, who gains fame as the "Sleeping Detective" due to Conan's covert interventions.

The series is structured around episodic mysteries, often involving murder or theft, which Conan unravels using his sharp intellect and deductive reasoning. These cases range from standalone incidents to multi-episode arcs, with Conan employing gadgets created by his inventor friend, Dr. Hiroshi Agasa, to aid in his investigations. Alongside the episodic format, an overarching narrative focuses on Conan's pursuit of the Black Organization, the group responsible for his transformation. This shadowy organization engages in criminal activities, and Conan's efforts to expose and dismantle it form a central thread throughout the series.

Key characters include Ran Mouri, who remains unaware of Conan's true identity but harbors feelings for Shinichi; Kogoro Mouri, whose bumbling nature contrasts with Conan's brilliance; and Ai Haibara, a former member of the Black Organization who also suffers from the same poison and becomes Conan's ally. Other recurring characters include the Detective Boys, a group of children who often accompany Conan on adventures, and various law enforcement figures who collaborate with him on cases.

The series blends mystery, suspense, and occasional humor, with a focus on intricate plotlines and character development. While the episodic cases provide self-contained stories, the ongoing conflict with the Black Organization adds depth and continuity, driving the narrative forward. "Detective Conan" has maintained its popularity over decades, appealing to fans of detective fiction and long-form storytelling.