L'inspector Yokomizo ha reunit els tres sospitosos de la mort d'en Ganji Tetsuyama: l'actor i l'actriu protagonistes de la pel·lícula "Les termes escarlata" i l'assistent d'aquesta última. Tots tres tenen algun motiu per matar la víctima, però en Conan ja ha deduït qui és l'autor del crim. Ara només cal explicar-li els fets a l'inspector Yokomizo amb la veu del Dr. Agasa. Però l'Ayumi l'enxampa mentre parla amb el transformador de veu.

在警方对三名嫌疑人进行侦讯时，他们三人反而相互指责并揭露对方的犯案动机，这时，有人在更衣室内发现了一个空瓶子，另外在湖面上还有漂浮的火柴棒，为了弄清真相，警方又找来工作人员进行对峙，然而，他们却表示并未发现异样，期间，女主演深汐的一句话点醒了柯南，在他的引导下，大家得知一整夜都呆在温泉里的人并不是凶手而是死者本人，那么，凶手到底是谁？在他的身上又有怎样的关键性证据？

As the police continue their investigation, they discover a plastic tea bottle filled with water in the dressing room, match cinders floating on the water, and Tetsuyuma's silver-gemed ring. It is also revealed that all the suspects have been seen in the hotel after the sauna was closed disproving their previous theory. Conan uses his voice changing bowtie to impersonate Agasa to reveal the one waiting on the veranda was the victim and the Tetsuyuma spotted heading to the sauna was the culprit Junsaku Tansawa in disguise. Conan explains Tansawa tricked the victim into staying in the women's sauna all night in order to see the naked Mishio Natori, the heroine; This is evidenced by the bottle in the dressing room which Tetsuyuma used to stay hydrated and the match cinders used to smoke his pipe. As evidence towards Tansawa as the culprit, Conan reveals that he was completely engrossed in pretending to be Tetsuyuma that he took the silver ring without noticing.

En poursuivant leur enquête, les policiers découvrent une bouteille de thé en plastique remplie d'eau dans la loge, des cendres d'allumettes flottant sur l'eau et la bague en argent de Tetsuyuma.

脚本家の鉄山厳治が殺害される密室殺人事件が発生。容疑者は女優の名取深汐、そのマネージャーの丹沢純作、俳優の寺堂雲平の３人。深汐は厳治と電話で話し、朝一番で女湯に来たら一緒に入ってあげるとウソをついた事を告白。３人には厳治を殺害する動機があった。コナンはある言葉をヒントに事件の真相に辿り着いて…。

하이바라가 사건을 해결하는 와중에 자신의 알몸을 본 것을 아무렇지 않게 얘기하는 코난에게 지능적인 복수를 하게 되는 에피소드.

Conan consigue resolver el caso, y Haibara tomará venganza de su pequeño incidente con Conan.