Shinichi, Ran and Kogoro are on a vacation aboard a cruise ship, but little do they know that the patriarch of the wealthy Hatamoto family is about to be murdered! All suspicions seem to turn to the new son-in-law Takeshi Hatamoto, but is he really the one responsible? With the perpetrator still on board, can Conan figure out who the real murderer is and solve the case before more lives are lost? \[Adapted from original manga MEITANTEI CONAN Volume 03.\]