A male body was found at a seashore in Hari Cove (玻璃ヶ浦), a fictional seaside town in Shizuoka Prefecture (静岡市), midway between Tokyo and Nogoya. The storyline developed around a 5th-grade boy Kyohei who met Manabu Yukawa (湯川学), a physicist and an Imperial University professor, on a train to Hari Cove where his uncle Shigehiro Kawahata and aunt Setsuko Kawahata run a rundown hotel named Green Rock Inn with their daughter Narumi Kawahata (川畑成実).
The discovery of the body looked like a mere accident that a tourist fell down to the cliff and killed himself. Yukawa, who was also called “Detective Galileo”, dug into the case and found that the it was connected to a murder case in Tokyo 16 years ago. Digging deeper, a lot of family secrets came into light.