Jimmy Kudo is a high school detective who helps the police solve cases. During an investigation, he is attacked by Gin and Vodka who belong to a syndicate known as the Black Organization. They force him to ingest an experimental poison called APTX 4869 to kill him without leaving evidence. A rare side-effect of the poison, however, transforms him into a child instead of killing him. Adopting the pseudonym Conan Edogawa, Kudo hides his identity to investigate the Black Organization.