Kogoro and Ran take the Detective Boys to an onsen in Kinosaki, Hyōgo so Conan can heal his sprained ankle. While there, Ran runs into a little girl named Haruna. Ran learns that Haruna by herself and accompanies her around Kinosaki and remains unaware that a mysterious man is secretly stalking the pair. While Kogoro is interviewed by a name named Kouichi Yumoto, Conan notices that Ran is missing from the group and asks the Detective Boys if they have seen her. Mitsuhiko shows them a photo he took and which reveals Ran chasing after Haruna in the background and a the mysterious man. Unable to contact Ran through her phone, they discuss the probability that the man has captured Ran and the girl. Heiji coincidentally runs into the group revealing that he was hired by Haruna's father, Shuuhei Tabuse, to search for her. Heiji takes Kogoro and Conan to meet Shuuhei in an attempt to find a clue on Haruna's motive for running away from home. Shuuhei reveals that Haruna was visiting a museum when an the "Rainbow Child", an art sculpture created by his ex-wife was stolen and Haruna was missing along with it. Elsewhere, the mysterious man uses a taser to incapacitate Ran and corners Haruna.

While driving home, Kogoro, Ran, and Conan witness a traffic collision between a green car and a red car. The man in the red car, Shun Hayami, dies from the collision due to his car catching fire. While the police interrogate Seiji Kurumatani, the man in the green car, he claims that he did not see the car at the intersection which caused the accident. Conan, suspecting a murder, mentions that they saw the two cars at a convenience store and the police question the store's owner to confirm this. The store owner tells them that he saw Hayami and Kurumatani arguing in front of his store. Conan confirms it is a murder and investigates the ashtray of the green car and finds the same cigarette brand as the one Hayami smoked. After tranquilizing Kogoro, Conan announces that Kurumatani planned the murder. He reveals Kurumatani, who is an auto mechanic, was repairing Hayami's red car and was lending Hayami his green car during the time. After the repairs were finished, he called Hayami to the convenience store so they could trade cars. Before arriving there, Kurumatani adjusted a billboard at the intersection where the collision would soon occur. The adjustment caused the billboard to reflect headlamp lights creating glare for Hayami which caused the accident. Kurumatani confesses to the murder and reveals that Hayami ran over his sister a year ago. When Hayami's car came into repairs, he knew Hayami was the murderer and began his plan for revenge.