Conan, Ran and, Kogorō are going back home with a big cruise ship, because Kogorō forgot the time of the last one. Ran sees a women crying and ask her what happened. She then said that she was only thinking about her parents who died last year ago in an accident. It turns out that the women's name is Natsue Hatamoto and her husband Takeshi Hatamoto came to check for her and ask her what's wrong. Natsue then grabbed Takeshi and tells Ran and Conan that they got married on Hatamoto Island which Ran ask why they have married on that island, which Natsue explains it to Ran. The head family Gōzō Hatamoto is yelling at his on-in-law Kitarō Hatamoto because he is angry why Conan, Ran and Kogorō are on the boat. Gōzō wishes to speak alone with Takeshi which he later comes to his room and they are talking to each other with shocking developments. During dinner, Takeshi returned which the butler Suzuki has been terrified about what he sees. Everyone rushes to the room of their father, in which they discover that Gōzō has been killed.