Believing Higashio Maria went to look for the treasure hidden by her late grandmother, Haibara, Genta, Ayumi, and Mitsuhiko visit her grandmother's home and begin deciphering the clues with Conan's help. Meanwhile, Kudo Yusaku and Kudo Yukiko begin acting to quell the commotion caused by Shinichi. Later, Yusaku and Yukiko go to see Conan and tell him they've identified the boss of the Black Organization...