Conan, Ran, and Sonoko are invited to the opening ceremony of a chocolate shop that is supported by the Suzuki Group. They meet a woman named Mayuko Sakura, the shop producer. Next they meet a man named Yukihiko Tsujimoto, the chocolatier and he's Mayuko's fiancé. During Tsujimoto's show, the fire breaks out in the shop, killing Tsujimoto. Was this a terrible accident or a planned murder?

Chiba is unable to recall Naeko's face though notes his familiarity. During the investigation, Conan realizes the culprit's motif and has the police let the suspects leave.