When Mori Kogoro's detective agency mistakenly receives a blackmail call, Conan recognizes the voice as his friend Heiji's from Osaka. The two high school detectives team up to crack the case of a stolen jewel, coveted not only by them but also by the infamous master thief Kaitou Kid. With 100,000 Yen at stake, Heiji and Conan race against time to outwit the competition and recover the precious gem.