The Scarlet School Trip (Bright Red Arc)

what happens

After receiving an antidote from Haibara, Conan temporarily turns back into Kudo Shinichi so he can go on the school trip to Kyoto with Ran, Sonoko, and Sera. Shinichi meets his mother's friend actress Kurachi Keiko at Kiyomizu Temple. She asks Shinichi to decipher a code delivered to her former college classmate Nishiki. While trying to crack the code, Shinichi receives a message from Keiko telling him to come to Nishiki's room, where he finds Nishiki lying on the floor upside down and bleeding from the chest with two bumps on his forehead...