The plot involves a large gem known as the "Blue Sapphire," which sank to the bottom of the ocean at the end of the 19th century. The film centers on Kaitō Kid, Makoto Kyōgoku, and Conan Edogawa. Makoto, an undefeated karate master with 400 wins, confronts Kid as Kid tries to steal the Blue Sapphire. Meanwhile, Kaitō Kid brings Conan to Singapore against his will. (Source: Anime News Network)