Finally, the time has come for the best showdown of our two heroes, Lupin and Conan! A big diamond has been stolen by the Magic Kid and he has managed to run off with it even under extremely tight security. This is followed by a big car chase throughout the city involving the Magic Kid and police. Through this great car chase, our hero Conan finds out that the criminal is not the Magic Kid but is actually Lupin the Third. Conan then realizes that Lupin is planning to steal his next treasure, a famous gorgeous treasure called the Cherry Sapphire, in order to help his girlfriend Fujiko who was abducted by the godfather. The following day the three kid detectives are watching the news on a great live event starring the famous idol singer Emilio. In the news Conan spots Lupin's partner in crime Jigen holding a gun as the singer's bodyguard. This makes Conan feel suspicious that Lupin and his fellow criminals may be scheming on a grand scale to steal the great treasure. These doubts turn into reality by them receiving a notice letter from the bold criminal called Lupin. The arch-rival of Lupin named Zenigata Inspector is excited with the prospect of arresting Lupin. But even with the help from his capable colleagues, he cannot do it and the great precious stone is stolen. In accordance with Lupin's promise with the godfather, the stolen treasure has been handed over to him. And now, the fight of the century, Conan vs Lupin, is about to unfold right in front of your very own eyes.