The detective boys are hiking on a trip to find stag beetles on a mountain forest. There Conan receives a photo of Ran in a swimsuit from Sonoko. Later Conan receives a phone call from Ran and Sonoko who tells "Shinichi" that a burglar tried to steal Sonoko's bag. Since it relates to a murder, Conan investigates the picture sent by Sonoko to learn about the dying message. While at it, he helps the Detective Boys solve one of Agasa's code.