Hiroshi Hamano, a professor at a medical university, is found dead. Going by the results of the autopsy, it appears he committed suicide by jumping off a roof, but going by eyewitness testimony and physical evidence at the scene, Detective Kamei suspects murder. A ticket for a train trip around Japan is found in the professor's pocket. However, nobody then could have known the shocking truth hidden behind the tour the dead man was supposed to attend...
