Conan, Ai and the Detective Boys bump into a drug dealer on the run. The drug dealer loses his notebook and Conan finds that there's a code inside about a drug exchange which is going to take place that same day. In order to stop it, they'll first need to solve the code and find the location and exact time of drug deal. The Detective Boys contact Heiji and they determine that the code is connected to the train networks for both of their cities.