El senyor Katayose convida en Kogoro, la Ran i en Conan a visitar casa seva, el Palau de les Fulles Vermelles, en agraïment per haver salvat la seva filla adoptiva Kaede. Un cop allà, el senyor Katayose apareix mort enverinat i en Conan intenta investigar un cas que d'entrada sembla molt complicat. Ningú no entén com s'ho ha fet l'assassí per sortir de l'escenari del crim sense que l'hagin pogut veure.

动画原创。资产家片寄王三郎在家中中毒身亡，而片寄留下了一封暗号信来提示自己的财产所在地。中北无意的话点醒了柯南，而就在这时牺牲者再一次出现！这次是野笛小姐被箭射中中毒身亡，而在附近的树屋找到了弓，而爱好弓的荻人成了头号嫌疑人但就在这时却传来荻人坠崖的消息。最终在柯南的推理下找出了犯人，而一场遗产争夺战也浮出水面。

Nobue is found dead with a poisoned arrow in her back while holding a clean arrow in her hand. Ogito's crossbow is found near the scene leading the police to suspect him. Later, Ogito falls down a cliff due to being shocked by an electric fence. Conan, realizing how the events transpired, tranquilizes Kogoro and reveals how the three died. Katayose poisoned himself and hoped to frame his children in order to protect Nakakita from their greed. Nobue, seeking to increase her inheritance, set up the crossbow and held an arrow in her hand to frame Ogito for attempted murder, but was instead murdered by Ogito. Ogito meanwhile, figured out the location of the treasure which is placed inside a cross made of metal rods. As he attempted to remove the treasure, Suzuka re-activated the electric fence which unintentionally resulted in his death. As for the treasure, it reveals Katayose leaves his inheritance to Nakakita who is actually his blood-related granddaughter from his former love.

Kogorô, Ran et Conan sont invités dans la demeure du magnat de l’immobilier, une demeure où règne les érables. Cependant, une affaire de meurtre en entraînant d’autres, bientôt, il n’y a plus grand monde à suspecter …

自分の部屋で変死した王三郎。庭にコナン、廊下に蘭がいた中での密室犯罪だった。小五郎は王三郎が残した暗号文の解読に取りかかる。コナンは暗号文の一部を解読。その直後、野笛の悲鳴が聞こえてくる。そしてコナンらは背中に矢が刺さって絶命した野笛を発見。さらに小五郎が犯人と疑う荻人が崖から転落して…。

자신의 방에서 죽은 오사부로. 뜰에는 코난, 복도에는 란이 있었던 때의 밀실 범죄였다. 코고로는 오사부로가 남긴 암호문의 해독에 착수한다. 그때, 오기히토와 노부에가 행방을 감춘 것이 드러난다. 한편 오기히토와 노부에는 암호문이 숨겨진 재산의 장소를 적어놓은 것이라고 생각했다. 그 후, 코난은 암호문의 일부를 해독한다. 그 직후, 노부에의 비명소리가 들려온다. 그리고 코난 일행은 등에 화살이 박혀 죽어있는 노부에를 발견한다. 게다가 코고로가 범인으로 의심하던 오기히토가 벼랑에서 떨어지는데...

Después del asesinato del patrón de la familia y de encontrar el código secreto que se deberá descifrar con los elementos representativos de la mansión, es decir con los árboles de hojas rojas. ¿Logrará Conan descubrir el código antes de los dos hijastros del patrón para conseguir la fortuna?