Conan, Ran, Sonoko, and Sera are invited to their classmate Sekizawa Yumi's birthday party. Because her older sister Sekizawa Remi the model's birthday is one day earlier, their joint birthday party is attended by numerous celebrities, Remi's manager Kushiyama Mitomu, Remi's classmate and pastry chef Hatsune Tsuguo, and hair and makeup artist Hanasaki Mizutoshi. Conan, who has trouble speaking due to the cold sore he developed several days earlier, takes out a pill case so he can take some medicine before the party starts when he's spotted by Sera. Inside the case is the APTX-4869 antidote Haibara gave him during his school trip...

Conan, Ran, Sonoko, and Sera attend the birthday party of their classmate Sekizawa Yumi and her older sister and model Sekizawa Remi. During the party, while the restaurant lights have been turned off for a slideshow, hair and makeup artist Hanasaki Mizutoshi, who had been hitting on the Sekizawa sisters, can be heard groaning in pain. When the lights come on, Hanasaki's dead body is on the floor. Furthermore, the words "divine punishment" have been written on his forehead... Meanwhile, Sera recalls the day her mother Mary was turned into a child.