The Detective Boy's have 24 hours to help a girl solve a riddle for her inheritance: "When the bull loses its horns, and his tail becomes his head. The angel will come down and play the horn. That melody is my treasure."

One day a man was jogging and finds a dead body. He calls the Ambulance but worried about the mans life, decides to run to the nearest bus station. Because of his actions he is considered the main suspect. Takagi comes to the case and with Conan's help, solves the case. He proves the mans innocence and captures the culprit. It turns out the Manger's dying message was for the culprit saying he should always try and smile.