Kogoro, Conan, and Ran are invited to dog food company president Anna's birthday party and arrive at the yacht harbor. Shortly after the party begins, Anna is shot to death by a masked man wielding a shotgun. Inspector Megure questions vice president Inamura, director Machiko, and secretary Morishima, and Anna's ex-boyfriend Hyodo emerges as a suspect. However, Hyodo has an alibi: he was robbing Anna's apartment. Kogoro and the police suspect he fabricated his alibi.

While playing soccer in the park, Conan, Mitsuhiko, Genta, Ayumi, and Haibara meet Komori Tomoko drinking wine alone. With tears streaming down her face, she confesses that her beloved boyfriend has passed away. Later, Tomoko takes the children to a botanical garden, where they meet Kajiki Kohei, the president of a men's cosmetics company. Tomoko and Kajiki hit it off, and the two begin dating. A few days later, Tomoko invites the children to her house to inform them of some exciting news. However, while ascending the stairs to the second-floor terrace, they hear a scream.