A high school boy named Jimmy Kudo changes his identity to Detective Conan after being shrunken to the size of a seven-year-old in a criminal attack, and starts helping police investigate a number of other crimes.

After a suspicious man transforms witty high schooler Jimmy Kudo into a puny grade schooler, the hapless boy finds a home with eccentric inventor Professor Agasa, who searches for a cure for his condition, and while he waits to be restored to his adolescence, Jimmy takes on the name Detective Conan and helps an incompetent private detective solve gruesome murder mysteries.