The episode begins with a secret organization called BLUE discussing an investigation into Ron Kamonohashi. They suspect him of working as a detective again and want to verify this. Meanwhile, Totomaru and Kamonohashi win a hot spring voucher in a raffle. Despite initial hesitation, they decide to go there. Upon arriving at the Benizome hot spring, they learn the legend behind its name. Long ago, the hot spring is said to have turned crimson from the sacrifice of a young woman. They check into the annex of the inn, where they meet other guests. The innkeeper deduces from the wear on Totomaru's shoes that he is a detective, but Kamonohashi dismisses it as a trick.

The duo enjoys the hot spring and discusses a secret legend about the crimson water, which Kamonohashi found in an old pamphlet. They also play "The Game of Life," where Kamonohashi wins and jokingly declares Totomaru his lifelong slave. Later, they join the other guests for dinner. Among them is Amamiya, a colleague who won the second prize in the raffle. After dinner, they continue playing "The Game of Life" and discuss the idea of reshaping their lives.

The mood darkens when one of the guests, Sachiko, is found dead in the women's restroom. Totomaru and Kamonohashi rush to the crime scene. Rigor mortis suggests she died between midnight and 2 a.m. Kamonohashi begins investigating, much to the annoyance of the inn's staff.

Amamiya becomes the prime suspect, as she was the only one who returned to her room before the deceased. However, Kamonohashi dismisses the accusation, stating she could not possibly have orchestrated the situation. He promises to prove her innocence and ends the episode on a cliffhanger.