Mitsuyo Matsuya's father quit his job one day and started trying to turn the house into a traditional inn. He even dug up the floor because he claims his ancestors told him in a dream that there was a hot spring there. Finally, one day he did indeed find a hot spring under the house. He was badly burned but to the horror of Mitsuyo and her mother, he refused to get treatment and wanted to keep going to turn the spring into a bath house. At this stage, Mrs. Matsuya left with her daughter.
In the present day, Mitsuyo recounts her past to a friend (possibly her boyfriend). He shows great interest and wants to visit the inn, but Mitsuyo refuses to go with him and warns of "strange customers" who were seen around the inn. Her friend goes to look for it and is told that it was closed down by the authorities; but finds the inn, now renamed "Hell's Bath House." Mitsuyo's hideously scarred and burned father says that the inn is still operating in secret.
Mitsuyo's friend sees horrendously deformed people all around the inn that he believes are the mysterious customers Mitsuyo spoke about. There is a strange smell in the bath house and the water is completely red like blood. He is told that it really is blood, and comes up from hell. There is a very wide, deep hole in the center of the spring where the steam comes from, and suddenly, a skeletal, corpse-like person emerges from it. Mitsuyo's friend observes that all the people in the spring look like this.
Many more such people emerge from inside the hole and climb out. Mitsuyo's friend realizes that the "hot spring" is actually a portal to hell. He refuses to describe what happened when the creatures reached the inn upstairs; but says that it was just like being in hell. Finally, he passes out. He wakes up to find the inn completely deserted, the water gone, and smoke and strange sounds still coming up from the hole.