The Sudden Street Car Stopping Case

Conan and the Detective Boys wake up at 5:30 in the morning to go get in line for a roller coaster ride. There are only three other people on the train, all of them are trainspotters. One of the photographers waits outside so he can take pictures of the train coming towards him; suddenly, the ladder underneath him tips over and he falls onto the track. The train conductor quickly applies the emergency brakes, and everybody rushes out of the train to find him unhurt. However, when Conan comes back into the train to continue their journey, they find one of the other photographers dead. How can Conan make the officer in charge of the case see sense that this was a murder, not an accident?