The Detective Boys, along with Rachel (Ran Mouri) and Richard (Mouri Kogoro), are at a beach one day when they come across two rich people; a snobby young man named Kogatsu, and a young woman named Shinobu. George finds an SOS in a bottle by Shinobu on a beach. They find her in a cave; reaching it by a raft. She explains Kogatsu tried to kill her by drugging her to sleep and letting the tides rise. The tides have risen to a point where they can not leave the cave. They venture into the maze of a cave and escape to a pool where they encounter Kogatsu and Richard (Mouri Kogoro). Kogatsu then holds Ayumi at gunpoint and threatens to kill everyone, but Rachel (Ran Mouri) and an old guard arrive in time to save them. In the end, Kogatsu is taken to jail as Shinobu looks sadly at the man who betrayed her love while Richard (Mouri Kogoro) is sternly lectured by the old guard for fishing in the pool, which is off-limits.