Japan's most famous detective, young Shinichi Kudo, witnesses a suspicious exchange between men dressed in black. After discovering it, Shinichi is attacked by one of those gangsters, and they administer a poison in order to kill him. However, the poison has an unexpected effect: Shinichi's body becomes that of a 7-year-old boy.

Now, calling himself Conan Edogawa and hiding his true identity in order to protect his family and himself from the Men in Black, the young detective moves to his father's house: Detective Kogoro Mouri. None of them know that Conan is, in fact, Sinichi and he will use his secret to solve Mouri's own cases without anyone knowing.