A murder case court is in session in which Toshio Iwamatsu is suspected of having killed Tadashi Ishigaki after burglarizing his home office.

Kogoro appears in a commercial to promote white chocolate for White Day and is invited to the chocolate company's White Day party. Kogoro, Ran, and Conan attend and are introduced to the company presidents, Taruto Urai and his wife Hoshie Urai. During the party, Taruto collapses. At first thought to be one of his practical jokes, Conan quickly notices that Taruto has died from cyanide poisoning.