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...