Ace high school detective Jimmy Kudo is renowned for his amazing powers of deductive reasoning. Hot on the trail of a pair of mysterious men in black, Jimmy is attacked from behind and is administered a strange substance which physically transforms him into a first grader. Until Jimmy can track down the sinister culprits and to find a cure for his most peculiar pint-sized condition, he takes on the pseudonym Conan Edogawa and solves all the cases that come his way. In this suspense-filled volume: Jimmy, Rachel and Richard take a vacation aboard a cruise ship - little do they know that the patriarch of the wealthy Hatamoto family is about to be murdered. With the perpetrator still aboard ship can you figure out whodunit before Conan does!?